curso heui.pdf

Service TrainingMeeting Guide 672 SESV1672-01

April 1997

TECHNICAL PRESENTATION

3408E/3412E ENGINE CONTROLS

HYDRAULIC ELECTRONIC UNIT INJECTION (HEUI)

PUMPCONTROL

VALVE

OILFILTER

OILCOOLER

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR

HYDRAULICTEMPERATURE

SENSORCOLD START

OILRESERVOIR OIL PRESSURE

SENSOR

ECM

HYDRAULICSUPPLY

PUMPGROUP

COOL DOWNCIRCUIT

FUEL TANK

FUELTEMPERATURE

SENSOR

PRESSUREREGULATING

VALVE

SECONDARYFUEL

FILTER

FUELTRANSFER

PUMP

PRIMARYFUEL FILTER

WATERSEPARATOR

LUBE OILPUMP

TO LUBESYSTEM

3408E/3412E HEUI FUEL SYSTEM

FLUID MANIFOLDHYDRAULIC PASSAGE


3408E/3412E ENGINE CONTROLSHYDRAULIC ELECTRONIC UNIT INJECTION (HEUI)

MEETING GUIDE 672 SLIDES AND SCRIPTAUDIENCE

Level II - Service personnel who understand the principles of engine systems operation, diagnosticequipment, and procedures for testing and adjusting.

CONTENT

This presentation is designed to prepare a service technician to identify the components, explain theirfunction, and service the 3408E/3412E Hydraulic Electronic Unit Injection (HEUI) engines in allcurrent machine and industrial applications.

OBJECTIVES

After learning the information in this presentation, the serviceman will be able to:

1. locate and identify the major components in the 3400 HEUI system;

2. explain the functions of the major components in the 3400 HEUI system;

3. trace the flow of oil through the engine hydraulic system;

4. trace the flow of fuel through the fuel system; and

5. trace the flow of current through the engine electrical system.

PREREQUISITES

Interactive Video Course "Fundamentals of Mobile Hydraulics" TEVR9001Interactive Video Course "Fundamentals of Electrical Systems" TEVR9002Programmed Instruction Course "Basic Electricity" SEBV0534STMG 546 "Graphic Fluid Power Symbols" SESV1546

Prior training in systems operation and testing and adjusting procedures for the 3408C/3412C enginesshould be completed before participating in this training session. Additionally, the participants shouldhave PC skills and have completed introductory training in Windows® software.

Estimated Time: 8 HoursVisuals: 138 (2 X 2) SlidesServiceman Handouts: 8 Drawings/Data SheetForm: SESV1672-01Date: 4/97

© 1997 Caterpillar Inc.

SUPPLEMENTARY TRAINING MATERIAL

Video Tape "3408E/3412E HEUI Service Introduction" SEVN3550Brochure "Caterpillar 3408E and 3412E Engines" LEDH6055ESTMG "Introduction to Electronic Technician" LEPV5155Brochure "Caterpillar Electronic Technician" NEHP5614Wall Chart "HEUI Fuel System" (small) LEWH6116Wall Chart "HEUI Fuel System" (large) LEWH6266Wall Chart "HEUI Engine" LEWH6740

Training Book "Easy Windows, 3.1 Edition" by Shelly O'HaraAvailable from:Prentice Hall Computer Publishing0-88022-985-3Attn: Order Dept.201 W. 103rd St.Indianapolis, IN 46290

Reference Book "Field Guide to Microsoft Windows 95" by Stephen L. NelsonAvailable from:Microsoft Press International at Fax No. (206) 936-7329Also available from bookstores

Training Book "Windows 95 for Dummies"Published by IDG BooksIDG Books World Wide Website: http://www.idgbooks.comAvailable from bookstores

RECOMMENDED HEUI TOOLING

Caterpillar Electronic Technician Single Use License JERD2124Caterpillar Electronic Technician Annual Data Subscription (All Engines and Machines) JERD2129

Communication Adaptor 7X1700PC to Communication Adaptor Cable 7X1425Communication Adaptor to Machine Cable 139-4166(combined ATA and CDL Data Link cable; replaces 7X1570 and 7X1412)Digital Multimeter (Fluke 87) 9U7330Cable Probes 7X1710

Hydraulic Unit Injector Puller 131-3921Hydraulic Unit Injector Sleeve Removal Wrench 111-5051

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REFERENCES

Troubleshooting Manual "3408E Engine--631E - 637E Wheel Tractor-Scrapers" SENR1037Troubleshooting Manual "3412E Engine--24H Motor Grader" SENR1038Troubleshooting Manual "3408E Engine--834B/836 Wheel Tractors" SENR1052Troubleshooting Manual "3408E/3412E Engines--D9R/D10R Track-type Tractors" SENR1054Troubleshooting Manual "3408E/3412E Engines--988F/990 Wheel Loaders" SENR1060Troubleshooting Manual "3408E/3412E Engines--769D - 775D Off-highway Trucks" SENR1062Troubleshooting Manual "3408E/3412E Engines--Industrial Applications" SENR1065Troubleshooting Manual "3408E/3412E Engines--651E - 657E Wheel Tractor-Scrapers" SENR1076

Disassembly and Assembly Manual "3408E/3412E Captive Engines" SENR1013Disassembly and Assembly Manual "3408E/3412E Industrial and Marine Engines" SENR1063

Testing and Adjusting Manual "3408E/3412E Engines--Captive Engines" SENR1018Testing and Adjusting Manual "3408E/3412E Engines--Industrial Engines" SENR1033

Electrical Schematic "3408E/3412E Captive Engines" SENR1026Electrical Schematic "3408E/3412E Industrial Engines" SENR1064

Special Instruction "Using the ECAP" SEHS8742Special Instruction "Installing the 7X1180 ECAP Expansion Board" SEHS8833

Tool Operating Manual "Using the Communication Adapter" SEHS9264Tool Operating Manual "Using the Machine Functions Service Program Module" SEHS9343

Parts Manual "3408E Industrial Engine" SEBP2509

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TABLA DE CONTENIDOS

INTRODUCCION..................................................................................................................7Vista Genreal ..........................................................................................................................8Compoentes Principales ...........................................................................................................9

SISTEMA DE CONTROL ELECTRONICO .......... ............................................................26Fuel Injection .................................................................................................................29Fuel Injection Control System .......................................................................................31

FUEL INJECTION SYSTEM .............................................................................................49System Components .......................................................................................................51System Operation ...........................................................................................................53Hydraulic Unit Injector Operation .................................................................................56Injector Operation Characteristics ..................................................................................61Injector Components ......................................................................................................64Injector Removal and Installation ..................................................................................68Injection Sequence .........................................................................................................71

HYDRAULIC SYSTEM......................................................................................................82Hydraulic Supply Pump Group ......................................................................................83System Operation ...........................................................................................................93

SYSTEM POWER SUPPLIES ..........................................................................................105ECM Power Supply .....................................................................................................106Speed/Timing Sensor Power Supply ............................................................................108Injector Power Supplies ..............................................................................................109Analog Sensor Power Supply ......................................................................................110Digital Sensor Power Supply .......................................................................................111Pump Control Valve Power Supply .............................................................................112

ELECTRONIC SENSORS AND SYSTEMS ....................................................................114Speed/Timing Sensors ..................................................................................................115Analog Sensors and Circuits ........................................................................................117Digital Sensors and Circuits .........................................................................................131Engine Shutdown Systems ...........................................................................................135Demand Fan Controls ..................................................................................................137Ether Injection System .................................................................................................138CAT Data Link .............................................................................................................139Logged Events ..............................................................................................................141

MACHINE APPLICATIONS ............................................................................................144D9R/D10R Track-type Tractors ...................................................................................145988F/990 Series II Wheel Loaders ..............................................................................149769C/771C/773B/775B Off-highway Trucks ..............................................................1523408E/3412E HEUI Industrial Engines .......................................................................155

SLIDE LIST .......................................................................................................................158

SERVICEMAN'S HANDOUTS ........................................................................................160

INSTRUCTOR NOTES

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1

3408E/3412E ENGINE CONTROLS

HYDRAULIC ELECTRONIC UNIT INJECTION(HEUI)

©1997 Caterpillar Inc.

INTRODUCTION

This presentation discusses the 3408E/3412E Hydraulic Electronic UnitInjection (HEUI) Engine Controls in all applications.

The topics are sequenced as follows:

- Introduction and Major Components

- Electronic Control System

- Fuel Injection System

- Hydraulic System

- System Power Supplies

- Electronic Sensors and Systems

- Machine Applications

INSTRUCTOR NOTE: This presentation refers to and describesElectronic Technician (ET) as the programming tool for the3408E/3412E engines. As new and more sophisticated electronicengine controls are now in use, the Electronic Control AnalyzerProgrammer (ECAP) is no longer adequate for all tasks (such as flashprogramming). The ET software, installed on a PC, is now theprinciple tool used in programming.

• Major topics

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• HEUI applications

• System features

2

Overview

The 3408E/3412E engines equipped with the HEUI fuel system areavailable in construction equipment and industrial applications.

Industrial engines are available in both 3408C/3412C (pump and line fuelsystem) and 3408E/3412E HEUI versions.

Caterpillar machines powered by the 3408E/3412E engines which featureHEUI include:

- 769D/771D/773D Off-highway Trucks

- 988F/990 Series II Wheel Loaders

- D9R/D10R Track-type Tractors

- 631E/637E/651E/657E Wheel Tractor-Scrapers

- 24H Motor Grader

The HEUI engines have many features and benefits not possible withmechanical fuel systems. These features include a very clean exhaust,improved fuel consumption and cold starting, simplified maintenancewith fewer moving parts, and reduced operating costs.

The system has additional advantages which will be covered later in thispresentation.

STMG 672 - 9 -4/97

3

• Electronically similarto EUI system

• Hydraulic pump raisespressure

• Hydraulic pressurecontrolled by ECM

• Injectorselectronicallysignalled

PUMPCONTROL

VALVE

OILFILTER

OILCOOLER

HEUI

HEUI

SUMINDERODE ACEITE

SENSOR DEPRESIONHIDRAULICA


SENSORCOLD START


SENSOR

ECM

HYDRAULICSUPPLY

PUMPGROUP

COOL DOWNCIRCUIT

TANQUE DE COMBUSTIBLE

FUELTEMPERATURE

SENSOR

VALVULAREGULADORA

DE PRESION

FILTROSECUNDARIO

DE COMBUSTIBLE

FUELTRANSFER

PUMP

PRIMARYFUEL FILTER

WATERSEPARATOR

LUBE OILPUMP

TO LUBESYSTEM




Major Components

This schematic shows the various components in the HEUI fuel system.A detailed explanation of the system and the various components followslater in this presentation.

The electronic components in the HEUI fuel system are very similar tothose used in other EUI systems. However, in the HEUI system, theinjectors are not actuated by a camshaft.

A high pressure hydraulic pump, which draws oil from the pressure sideof the lubrication pump, raises the pressure to a maximum of 22800 kPa(3300 psi). The pressure is controlled by the Electronic Control Module(ECM). The hydraulic flow is directed to hydraulic actuators in eachinjector.

The injectors are electronically signalled (as in the EUI system) to permitoil under high pressure to move a piston which then moves the fuelplunger.

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• Siete t ipos de componentes principales

1. Hydraulic supplypump group

2. ECM

3. Throttle control

4. Speed/timingsensor

5. Injector

6. Temperaturesensor

7. Pressure sensor

• CAT Data Link andcoolant flow switch(not shown)

4

2

3

456

7

1

This slide shows seven of the major types of components in the HEUIfuel system.

• Hydraulic Supply Pump Group (1) containing:

- High pressure hydraulic pump

- Pump control valve

- Transfer pump

• ECM (2)

• Throttle Control (3)

• Speed/Timing Sensor (4)

• Injector (5)

• Temperature Sensor (6)

• Pressure Sensor (7)

The CAT Data Link (not shown) provides a two-way communication pathbetween the HEUI system and the remaining electronic circuits orsystems on the machine. The CAT Data Link also allows the service toolto communicate with the engine electronic system.

NOTE: Only one example of each sensor (pressure, temperature andspeed/timing) is shown on the slide.

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• 3400 HEUI engine topview

1. ECM--the "heart"of the system

• Personality moduleaccess panel locatedbelow ECM


• Wiring harness

5

1

2222

The principal component in the HEUI system, the Electronic ControlModule (1), is mounted on top of the right front valve cover.

The ECM is the "heart" of the engine. The ECM performs enginegoverning, timing and fuel limiting. It also reads sensors andcommunicates to the instrument display system through the CAT DataLink.

The Personality Module is used to program the ECM with all the ratinginformation for a particular application. The Personality Module can bechanged by direct replacement or can be flash programmed(reprogrammed) using a PC. The Personality Module Access Panel islocated below the ECM.

The Hydraulic Supply Pump Group (2) is mounted in the vee of theengine in the same position as the original fuel pump and governor for the3408C/3412C engines. Flow from this pump supplies the actuatingpressure for the injectors. Mounted on the rear of the pump is the fueltransfer pump.

Among the visible components are the Wiring Harness and 40 PinConnectors to the ECM.

INSTRUCTOR NOTE: The slides which follow show machine andindustrial engines. The physical appearance and function of theHEUI machine and industrial engine components are very similar.

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• Engine upper left sideview

1. Fuel temperaturesensor

2. Atmosphericpressure sensor

3. Lubrication oilpressure sensor

4. Hydraulictemperature sensor

5. Machine interfaceconnector

6. Ground bolt

6

12 4

53

6

This view from the upper left side of the engine shows the FuelTemperature Sensor (1). The Atmospheric Pressure Sensor (2) ismounted on the Hydraulic Supply Pump Group mounting adapter.

Mounted on the Hydraulic Supply Pump Group is the Lubrication OilPressure Sensor (3). The sensor is used by the ECM to generate a lowoil pressure warning for the operator.

Also mounted on the Hydraulic Supply Pump Group is thelUBRICATIONTemperature Sensor (4). This sensor is used by the ECM for viscositycompensation to maintain consistent fuel delivery and injector timingregardless of viscosity changes caused by varying hydraulic temperatures.Both sensors are threaded into the supply pump case.

The 40 Pin Machine Interface Connector (5) is mounted behind theHydraulic Supply Pump Group. This component makes the connectionbetween the engine and machine wiring harnesses.

A vital part of the wiring assembly is the Ground Bolt (6) mounted onthe machine interface connector bracket.

NOTE: Oil flow from the Hydraulic Supply Pump Group will bereferred to as "hydraulic" to avoid confusion with the lubricationsystem.

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1. Timing calibrationconnector

2. Hydraulic pressuresensor

3. Injector connector

7

2

13

The Timing Calibration Connector (1) is located adjacent to the ECM.

The Hydraulic (Injection Actuation) Pressure Sensor (2) is locatedbetween the valve cover bases in the right Fluid Supply Manifold.

The Injector Connector (3) is one of four connectors on a 3408E. (Each connector supplies current to two injector solenoids.)

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• Coolant temperaturesensor (arrow)

8

The engine Coolant Temperature Sensor (arrow) is located in the frontof the right cylinder head. This sensor is used with the ECM to controlvarious functions. The following systems or circuits use the TemperatureSensor output to the ECM:

The Vital Information Management System (VIMS) or CaterpillarMonitoring System Coolant Temperature Gauge over the CAT DataLink.

The High Coolant Temperature Warning Alert Indicator LED andGauge on the VIMS or Caterpillar Monitoring System panel. (Theinformation is transmitted over the CAT Data Link.)

The Engine Demand Fan Control, if installed, uses the sensor signalreference to provide the appropriate fan speed.

The Cat Electronic Technician (ET) status screen coolant temperatureindication.

The Coolant Flow Switch (not visible in this view) is mounted below thecoolant temperature sensor at the inlet to the oil cooler.

• Coolant flow switch(not visible)

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• Secondaryspeed/timing sensor(arrow)

9

This view shows one of the Speed/Timing Sensors (arrow). A sensor ismounted on each side of the timing gear housing. This slide shows thesecondary Speed/Timing Sensor. The primary Speed/Timing Sensor islocated closest to the ECM.

These sensors are used to calculate engine speed and crankshaft positionfor timing purposes.

The sensors are self-adjusting, but special precautions are necessaryduring installation to prevent damage. (The precautions are describedlater in the presentation.)

NOTE: The sensors maintain a zero clearance with the timing wheel.

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• Rueda de Sincronizacion

• Marca de sincronizacion

10

Esta es la rueda de sincronizacion, fuera del motor

Notice the wide 50/50 size slot and equal size tooth (arrow) cut in thewheel. Las otras 23 ranuras son de tamaño 80/20

La ranura y diente 50/50 es usada po elECM como punto de referencia paradeterminar la posocion del motor para la sincronizacion del combustible (se explica completamente mas adelante). El sensor de Speed/Timing puedeidentificar este diente porque crea una señal diferente que los otros dientes

Una marca de sincronizacion "H," al reverso de larueda de sincronizacion es usada parasincronizar la rueda en relacion a los otros engran. de sincroniz. y el TDC del cigueñal.

• Ranura y diente 50/50(fecha)

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• Turbo inlet pressuresensor (arrow)

11

The Turbo Inlet Pressure Sensor (arrow) is mounted between the airfilter and the turbocharger. Not all machines have this sensor installed.

This sensor (if installed) is used in conjunction with the atmosphericpressure sensor to measure air filter restriction for engine protectionpurposes. The difference between the two pressure measurements is usedas the filter differential pressure.

The engine ECM uses this calculation to determine whether derating isnecessary to protect the engine.

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• Turbo outlet pressuresensor (arrow)

12

At the front of the engine in the right cylinder head is the Turbo Outlet(Boost) Pressure Sensor (arrow). This sensor is used with the ECM tocontrol the air/fuel ratio electronically. This feature allows very precisesmoke control, which was not possible with mechanically governedengines.

The sensor also allows boost pressure to be read using the service tools.

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• Identify components:

1. Atmosphericpressure sensor

2. Fuel temperaturesensor

3. Primaryspeed/timingsensor

4. Secondaryspeed/timingsensor

13

1

2

43

The Atmospheric Pressure Sensor (1) is installed on the HydraulicSupply Pump Group adapter and is vented to the atmosphere. This sensorhas various functions which are fully described later in the presentation.A foam block below the sensor helps prevent the entry of dirt into thesensor.

Briefly, the sensor performs the following functions:

- Ambient pressure measurement for automatic altitudecompensation and automatic air filter compensation.

- Absolute pressure measurement for the fuel ratio control, ET,Caterpillar Monitoring System panel (gauge) pressurecalculations.

The Fuel Temperature Sensor (2) is used for automatic fuel temperaturecompensation.

The Primary (3) and Secondary (4) Speed/Timing Sensors (discussedearlier) are located on the rear of the timing gear housing.

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1. Aceite de suministro

2. Valvula Compensadora

3. Valvula de control bomba

4. Bomba trasnferencia

14

4

3

2

1

A number of components are mounted on the Hydraulic Supply PumpGroup. The Oil Supply Line (1) from the oil gallery is a large diameterline for maximum delivery during cold operation. The hydraulic pumpdepends on the lubrication pump for the first stage of pressure increase.

The Compensation Valve (2) is mounted at the rear of the pump. Belowthe compensation valve is the Pump Control Valve (3). This valve mayalso be referred to as the "injection actuation pressure control valve."This valve controls the angle of the swashplate, which varies the output ofthe pump.

The Fuel Transfer Pump (4) is mounted at the rear of the HydraulicSupply Pump and is driven by the main drive shaft which extends throughthe supply pump.

Also visible in this slide are the transfer pump inlet and outlet fuel linesand the pressure and temperature sensors (discussed earlier).

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• Lubrication oil pump

• Supplies oil tolubrication andhydraulic injectionactuation systems

15

Mounted internally in the oil pan is the Bomba de aceite de lubricacion. Thispump supplies oil at approximately 400 kPa (65 psi) to the oil gallery forengine lubrication.

Oil is also supplied to the hydraulic pump for injection actuationpurposes. For this reason, the HEUI engine lubrication oil pump is largerthan the pump in the previous engine to accommodate the increased needsof the lubrication and the hydraulic injection actuation systems.

STMG 672 - 22 -4/97

• Timing calibrationsensor (arrow)

16

The Timing Calibration Sensor (arrow) is installed when required in theflywheel housing.

This sensor (magnetic pickup) is installed in the hole normally reservedfor the timing pin. (The pin is used to position the crankshaft with theNo. 1 piston at top dead center.)

NOTE: On some applications (i.e. some track-type tractors) whereaccessibility is limited, this sensor is permanently installed.

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1. Water separatorand primary filter

2. Two micronsecondary filter

• Water separatorservice intervals

17

1

2

The Water Separator (1), which also functions as a Primary Fuel Filter,is an important part of the fuel system.

As with any high pressure fuel system with operating pressures atapproximately 150000 kPa (22000 psi), fuel quality is important. Waterin the fuel can cause corrosion of the plungers and barrels. Dirt can causeearly hour wear on the same components. The water separator contains a30 micron filter. The Priming Pump is mounted on the filter base.

For the same reason, the correct two micron Secondary Filter (2) mustbe used in the system. The clearance between the plunger and barrel isapproximately 5 microns. Typically, the 3 to 8 micron abrasive materialprematurely wears out the fuel system components.

The Water Separator is serviced daily by draining the water. The WaterSeparator filter is serviced with a new element every 500 hours.

INSTRUCTOR NOTE: The high fuel pressures mentioned in thistext are mandated by the need to meet environmental regulations forsmoke and emissions. Also, to maintain good fuel consumption, highpressures are required. The HEUI system meets and surpasses thoserequirements.

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18

• Engine componentidentification

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH

TURBO OUTLET PRESS. SENSOR

SECONDARYSPEED/TIMING SENSOR

PRIMARYSPEED/TIMING SENSOR

HYDRAULICPRESSURE SENSOR

24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS

PUMP CONTROL VALVE

COOLANT TEMP. SENSOR

ATMOSPHERIC PRESS. SENSOR

OIL PRESSURE SENSOR

HYDRAULIC TEMP. SENSOR

FUEL TEMPERATURE SENSOR

COOLANT FLOW SWITCH

8 OR 12INJECTORS

TDC SERVICEPROBE ACCESS

INSTRUMENTPANEL

AUTO RETARDER CONTROL

EPTC II TRANSMISSION CONTROL

ELECTRONIC SERVICE TOOL

CAT DATA LINK

FAN

FAN SPEED SENSOR

FAN CONTROL VALVE

TURBO INLET PRESSURE SENSOR

THROTTLE BACK-UP, ELEVATED LOW IDLE ENABLE,AND GROUND LEVEL SHUTDOWN (2) SWITCHES

THROTTLESENSOR ACCELERATOR

PEDAL

DISCONNECT SWITCH

3408E/3412E HEUI SYSTEMCOMPONENT DIAGRAM

MACHINEHARNESS

This schematic identifies the external HEUI engine components (shownon the engine harness side of this schematic). The components shown onthe left side of the diagram are mounted on the engine and those on theright are machine mounted. Notice that the turbo inlet pressure sensor ismounted on the machine.

INSTRUCTOR NOTE: At this time, it is recommended that eachcomponent be located on the machine and the function of eachreviewed with the students. A list of the components follows on thenext page.

Some additional (used/defective) components available forexamination on a table will be helpful. An ECM with the PersonalityModule and various sensors can be examined at this time and usedfor troubleshooting exercises later.

➥

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Electrical Components

Conector del ECM 40 Pins

Modulo de Personalidad

Timing Calibration Connector and Installation Location

Sensor de presion hhidraulica

Sensor de Temperatura Hidraulica

Primary Speed Timing Sensor

Secondary Speed Timing Sensor

Sensor de Temperatura de Refrigerante

Sensor de Presion Atmosferica

Sensor de presion de entrada del turbo

Sensor de presion de salida del turbo

Sensor de presion de aceite

Sensor de Temperatura de combustible

Switch de flujo de refrigerante

Conector de interfase a la maquina

Pernos de tierra de motor y de maquina

Conector al Data Link

Sensor de posicion de acelerador

Switches de apagado

Componentes Mecanicos

Grupo de bomba de suministro de aceite

Valvula de control de la bomba

Valvula de Compensacion

Reservorio para arranque en frio

Valvulas check

Manifold de fluido

Filtro Primario / Separador de agua

Filtro secundario

Bomba de transferencia

Valvula Reguladora de presion

Inyector

Tubo Jumper

Adaptador de aceite para inyector

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19

SISTEMA DE CONTROL DE ELECTRONICO

ELECTRONIC CONTROL SYSTEM

This section of the presentation explains the Electronic Control Systemincluding the following components:

ECM

Personality Module

Hydraulic Electronic Unit Injector Solenoids

Timing Wheel

Also covered are the following subsystems and related procedures:

Timing control

Fuel quantity control

Speed control

Cold modes

Timing calibration

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• ECM:

- Governor

- Fuel systemcomputer

- Injection pressurecontroller

- Injection timingcontroller

• Same ECM used in allapplications

20

The Electronic Control Module (ECM) functions as the governor and fuelsystem computer. The ECM receives all the signals from the sensors andenergizes the injector solenoids to control timing and engine speed.

The ECM is sealed except for access to the software which is contained inthe Personality Module (next slide). This ECM is the second generationof Advanced Diesel Engine Management Systems and may be frequentlyreferred to as "ADEM II."

This ECM is used in all applications of the 3408E and 3412E engines.The ECM can also be moved from one application to another; however, apassword is required to activate the ECM when new software is installed.

NOTE: The ECM has an excellent record of reliability. Therefore,any problems in the system are most likely to be in the connectorsand wiring harness. In other words, the ECM should typically be thelast item in troubleshooting.

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• Personality modulecontains software

• Two methods toupgrade software

• ECM is sealed exceptfor personality module

21

The Personality Module (shown removed from the ECM) contains thesoftware with all the fuel setting information (such as horsepower, torquerise and air/fuel ratio rates) which determines how the engine willperform. The Personality Module is installed on the lower face of theECM, behind the access panel.

At this time, two methods can be used to update the software:

1. Flash Programming: Electronic reprogramming of the PersonalityModule software. (This method is preferred when updating thesoftware.)

2. Remove and replace the Personality Module. (This method maybe used if Flash Programming is not possible.)

Upgrading the software is not a routine task, but might be performed forreasons of a product update, a performance improvement or a productproblem repair.

NOTE: The ECM is sealed and needs no routine adjustment ormaintenance. The Personality Module is mounted within the ECM.Installation of the Personality Module is the only reason to enter theECM. This operation would normally be performed during an ECMinstallation or a software update.

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• Unit injectors

• Electrically signalled,hydraulically actuated

22

Fuel Injection

The 3400 HEUI unit injector is electrically similar to the 3500 electronicunit injector. The injector is controlled electrically by the ECM but isactuated hydraulically. The signal from the ECM controls the openingand closing of the solenoid valve. The solenoid valve controls the flow ofhigh pressure hydraulic oil to the injector. This system enables the ECMto control fuel volume, timing and injection actuation pressure (hydraulicsupply pump pressure).

The injector solenoids operate on 105 Volts direct current. Alwaysremain clear of the injector area when the engine is running orelectric shock may occur.

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• Injector testing

23

PRUEBA DE SOLENOIDES DE INYECTOR

CORTE DE CILINDROS

PRUEBA AUTOMATICA DE INYECTORES

METODOS DE PRUEBAS EN INYECTORES HEUI

Three tests can be used to determine which cylinder or injector ismalfunctioning:

INJECTOR SOLENOID TESTThis test is performed while the engine is stopped. The injector solenoidscan be tested automatically with the service tool using the InjectorSolenoid Test. This function individually tests each solenoid in sequenceand indicates if a short or an open circuit is present.

CYLINDER CUT-OUT (Manual test)This test is performed while the engine is running at any speed. The 105 Volt pulse can be individually cut out to aid in troubleshootingmisfire problems in the injector and the cylinder.

AUTOMATIC INJECTOR TESTThis test is performed with the service tool while the engine is running atany speed. The test makes a comparative evaluation of all injectors andnumerically shows the results. The test enables an on-engine evaluationof the injectors. (This test cannot be performed using the ECAP.)

A satisfactory test of all injector solenoids without any diagnosticmessages indicates that a mechanical problem in the cylinder probablyexists.

STMG 672 - 31 -4/97

24

• Fuel timing control

• Inputs to timingcontrol

• Benefits of a "smart"timing control

LOGICA DE CONTROL DE HEUI

VELOCIDAD DE MOTOR

CANTIDAD DE COMBUSTIBLE FUEL RPM

MODO FRIO

SELECTTIMING

CONVERTDESIREDTIMING

TEMPERATURA DEACEITE A ALTA PRESION

TIMING CONTROL

DEGREES BTDC DESIREDTIMINGBTDC

TIMING

FUEL INJECTIONTIMING WAVE FORM

Fuel Injection Control System

This diagram shows the timing control logic within the ECM.

Engine speed, fuel quantity (which relates to load), and hydraulic oiltemperature input signals are received by the timing control. Thehydraulic temperature signal determines when the Cold Mode should beactivated. These combined input signals determine the start of fuelinjection.

The timing control provides the optimum timing for all conditions. Thebenefits of a "smart" timing control are:

- Reduced particulates and lower emissions

- Improved fuel consumption while still maintaining performance

- Extended engine life

- Improved cold starting

STMG 672 - 32 -4/97

25

• Fuel quantity control

• Inputs to fuel quantitycontrol

• Start of injectiondetermines timing

• Injection duration andinjection actuationpressure determinefuel quantity

ELECTRONICGOVERNOR

TORQUEMAPS

FRCMAPS

TURBO OUTLET ANDATMOSPHERIC

PRESSURE SENSORS

ENGINECONTROL

LOGIC

THROTTLE

SHUTDOWNS

INJECTIONACTUATIONCONTROL

ENGINE RPM

TDC

87654321

FUELINJECTIONCONTROL

TO PUMPCONTROL VALVE

SIGNALSTO FUEL

INJECTORS

SPEED/TIMINGSIGNAL

ENGINE RPM

SPEED/TIMINGSENSORS

TIMINGWHEEL

ENGINE RPM

ECM

3408E/3412E ELECTRONIC GOVERNOR

HYDRAULIC OILTEMPERATURE ANDPRESSURE SENSORS

Four inputs control fuel quantity:

1. Engine speed

2. Injection actuation (hydraulic) pressure

3. Throttle position

4. Boost

These signals are received by the electronic governor portion of the ECM. The governor then sends the desired fuel signal to the fuel injection andinjection actuation controls. The fuel quantity control logic also receivessignals from the fuel ratio and torque controls.

Three variables determine fuel quantity and timing:

- The start of injection determines engine timing.

- The injection duration and injection actuation (hydraulic)pressure determine the quantity of fuel to be injected.

STMG 672 - 33 -4/97

26

• Speed/timing sensors

• Three functions of thespeed/timing sensor

• Sensor installation

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH





24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS

PUMP CONTROL VALVE



OIL PRESSURE SENSOR



COOLANT FLOW SWITCH

8 OR 12INJECTORS


INSTRUMENTPANEL




CAT DATA LINK

FANFAN SPEED SENSOR

PROPORTIONAL VALVE



THROTTLESENSOR

ACCELERATORPEDAL

DISCONNECT SWITCH

HEUI SYSTEMCOMPONENT DIAGRAM

MACHINEHARNESS

Two Speed/Timing Sensors are installed: a primary and a secondary. TheSpeed/Timing Sensors serve three functions in the system:

1. Engine speed measurement

2. Engine timing measurement

3. Cylinder and TDC location

The Speed/Timing Sensors, which are mounted on the front housingbelow the timing gear wheel, are self-adjusting during installation andhave zero clearance with the timing wheel.

The head is extended prior to installation. The action of screwing in thesensor pushes the head back into the body until the head contacts thetiming wheel. This contact is only momentary while the engine isstarting. After start-up, the head runs with zero clearance.

STMG 672 - 34 -4/97

27

• Primary sensor

• Secondary sensor

• Power supply

393229381812

732-PK996-GN998-BR999-WHF723-PKF724-PU

SECONDARY ENGINE SPEED+V TIMINGDIGITAL RETURNPRIMARY ENGINE SPEEDTIMING CAL +TIMING CAL -

ECM(3408E/3412 E)

P2 J2

ABC

ORBKWH

SECONDARYSPEED/TIMING

SENSOR

ABC

ORBKWH

PRIMARYSPEED/TIMING

SENSOR

TIMING CALIBRATIONCONNECTOR

12

SPEED/TIMING SENSORS

P44 J44

P20 J20

P26 P1 J1

The Primary Speed/Timing Sensor (right side of engine) measures enginespeed for governing, and crankshaft position for timing purposes andcylinder identification.

The Secondary Speed/Timing Sensor (left side of engine) allowscontinuous operation if the primary sensor fails. A failure of the primarysensor will cause the ECM to automatically switch to the secondarysensor. Also, the check engine lamp will come on.

The ECM supplies 12.5 ± 1 Volts to the Primary and SecondarySpeed/Timing Sensors.

Connectors A and B transmit the common power supply to the sensors.The C connectors transmit separate signals from each sensor to the ECMfor back-up purposes.

NOTE: The Speed/Timing Sensors have a dedicated power supply.No other circuits should be spliced into this power supply.

STMG 672 - 35 -4/97

• Timing wheel

28

The Timing Wheel is an integral part of the drive gear for the pump.Timing marks are used to locate the wheel in the correct position relativeto the crankshaft. This Timing Wheel is common to all 3408E/3412Eengines.

As previously stated, the Timing Wheel has a total of 24 teeth. 23 teethare large with small spaces between them (80/20 relative size).

The other tooth and space have equal dimensions (50/50 relative size).This configuration is used by the ECM to locate TDC on the No. 1cylinder.

NOTICE

The head of the sensor MUST NOT be positioned in the timing wheel(wide) slot during installation. Incorrect positioning will causedamage to the sensor head.

STMG 672 - 36 -4/97

29

• Sensors generate aPWM signal fromtiming wheel teeth

• Failure modes

4

3

6

5

7

2

1

8

REF

REF

REF

REF

REF

REF

REF

REF

TDC

TDC

TDC

TDCTDC

TDC

TDC

SINGLE50/50 TOOTH

TIMING WHEELROTATION

TDC CYLINDER No. 1

TIMINGCALIBRATIONRANGE ± 10°

PRIMARYSPEED/TIMING

SENSOR


SENSOR

TIMING WHEEL

The Speed/Timing Sensors are positioned vertically over the teeth.

The teeth and sensors generate a Pulse Width Modulated (PWM) outputsignal for the purpose of timing and a frequency modulated output signalfor speed measurement.

The Secondary Speed/Timing Sensor functions the same as the primarysensor. The Secondary Speed/Timing Sensor is used when the signal fromthe primary sensor is lost or distorted. If the secondary sensor is selected,it will continue in use until the engine is shut down and cranked. Then,the primary sensor will be selected.

Unless the engine is cranking, the ECM will not switch from thesecondary to the primary sensor. This feature prevents constant switchingbetween sensors if an intermittent fault occurs.

INSTRUCTOR NOTE: A description of PWM signals is providedlater in this presentation (Sensors and Systems).

STMG 672 - 37 -4/97

30

• Cranking

• Timing wheel teethand spacing

A B C D E F G

TIMING WHEEL ROTATION

H

80/20 % 80/20 % 80/20 %80/20 % 50/50%80/20 % 80/20 %

TIMING GEAR TOOTH TABLE

TABLEENTRY

CYLINDERREFERENCE

ABCDEFGH

80 %80 %80 %80 %80 %80 %80 %50 %

CRANKING

NONE IDENTIFIED

PWM DUTYCYCLE

The Speed/Timing Sensor uses the timing wheel with the teeth arrangedas shown to determine:

- Top Dead Center No. 1 (When found, the cylinders can beidentified.)

- Engine speed

The sequence of signals shown in the second column (duty cycle) isanalyzed by the ECM. At this point, no fuel will be injected until certainconditions have been met.

Unlike EUI engines, this engine does not rely on tooth configuration toprevent reverse rotation. The lubrication and the hydraulic pumps will notdevelop pressure during reverse rotation, and will not move the injectorsto pump fuel. Therefore, the engine cannot run in reverse.

STMG 672 - 38 -4/97

31

• After patternrecognition

• Initial firing sequence


CYL NO. 3REFERENCE

EDGE

CYL NO. 4TDC

CYL NO. 4REFERENCE

EDGE

CYL NO. 8REFERENCE

EDGE

CYL NO. 3TDC


CYLINDERREFERENCE

80 %80 %80 %80 %80 %80 %80 %50 %

AFTER PATTERN RECOGNITION

NOCYL NO. 3NONOCYL NO. 4NONOCYL NO. 8

TABLEENTRY

ABCDEFGH

PWM DUTYCYCLE

A B C D E F G H

During start-up, the sensor initially monitors the pulses created by thepassing teeth and identifies the sequence as shown. After a completerotation, the control can recognize the location of TDC from the pattern inthe above illustration.

During initial cranking, no fuel is injected until:

The timing wheel has completed a full revolution.

TDC for all cylinders is identified by the control.

After the sensor has provided the necessary signals, the ECM is ready tostart injection (if sufficient hydraulic pressure is available to the injectors).

NOTE: The reference points in the illustration are positions on thetiming wheel from which the control measures the point of injectionand TDC.

STMG 672 - 39 -4/97

32

• Normal operation

• Signal patternidentifies TDC

• Conditions forinjection


PWM DUTYCYCLE

CYLINDERREFERENCE

80 %80 %80 %80 %80 %80 %80 %50 %

NORMAL OPERATIONNOCYL NO. 3NONOCYL NO. 4NONOCYL NO. 8

CYL NO. 4(REFERENCE)

CYL NO. 4ACTUAL TDC

(CALIBRATED)

62° BTDC (EEPROM)

DES TIMING

NO. 4INJECTION

TABLEENTRY


ABCDEFGH

A B C D E F G H

CYL NO. 3(REFERENCE)

CYL NO. 3ACTUAL TDC

(CALIBRATED)

62° BTDC (EEPROM)

DES TIMING

DELAY NO. 3INJECTION

DELAY

ASSUMEDTDC

ASSUMEDTDC

During normal operation, the ECM can determine timing from thesequence reference point for each cylinder. The reference point is storedby the ECM after calibration is performed.

Injection timing is calibrated by connecting a TDC probe to the serviceaccess connector on the engine harness, and by activating the calibrationsequence with the Caterpillar ET service tool. The ECM raises the enginespeed to 800 rpm (to optimize measurement accuracy), compares theactual No. 1 TDC location to the assumed cylinder No. 1 TDC location,and saves the offset in the EEPROM (Electrically Erasable ProgrammableRead Only Memory).

NOTE: The calibration offset range is limited to ± 10 crankshaftdegrees. If the range is exceeded, the offset is set to zero (nocalibration) and a calibration diagnostic message is generated.

STMG 672 - 40 -4/97

33

• Timing calibrationsensor

393229381812

732-PK996-GN998-BR999-WHF723-PKF724-PU


ECM(3408E/3412E)

P2 J2

ABC

ORBKWH


SENSOR

ABC

ORBKWH

PRIMARYSPEED/TIMING

SENSOR

TIMING CALIBRATIONCONNECTOR

P26

TIMING CALIBRATIONSENSOR

TIMING CALIBRATION SENSOR

P44 J44

P20 J20

P1 J1

12

The Timing Calibration Sensor (magnetic pickup) is installed in theflywheel housing during calibration. The connector is located above theECM. (On some machines, i.e. D9R/D10R, the sensor is permanentlyinstalled.)

Using the Caterpillar ET service tool, timing calibration is performedautomatically for both sensors when selected on the appropriate screen.

The desired engine speed is set to 800 rpm. This step is performed toavoid instability and ensures that no backlash is present in the timinggears during the calibration process.

STMG 672 - 41 -4/97

34

• Timing calibration

• Nulls out smallcrankshaft to timinggear tolerances

REFERENCE EDGE TO TDC DISTANCE

REFERENCEEDGE ASSUMED

CYL. NO. 1 TDCACTUAL

CYL. NO. 1 TDC

TIMINGREFERENCE

OFFSET

MAXIMUM TIMING REFERENCE OFFSET ± 10 DEGREES

TIMING CALIBRATIONSENSOR SIGNAL

TIMINGWHEEL

TIMING CALIBRATION

+10°

± 10°

-10°

As the Speed/Timing Sensors use the timing wheel for a timing reference,timing calibration improves fuel injection accuracy by correcting for anyslight tolerances between the crankshaft, timing gears and timing wheel.

During calibration, the offset is logged in the control module EEPROM(Electrically Erasable Programmable Read Only Memory). Thecalibration offset range is limited to ± 10 crankshaft degrees. If timing isout of range, calibration is aborted. The previous value will be retainedand a diagnostic message will be logged.

Timing calibration is normally performed after the following procedures:

1. ECM replacement

2. Speed/timing sensor replacement

3. Timing wheel replacement

STMG 672 - 42 -4/97

35

• Unit injector currentflow

INJECTION CURRENT WAVEFORM

0 1 2 3 4

CU

RR

EN

T

FL

OW

TIME (MILLISECONDS)

PULL-IN PEAK CURRENT

HOLD-IN PEAK CURRENT

ONE CYCLE

5

This illustration shows how the current increases initially to pull in theinjection coil and close the poppet valve. Then, by rapidly chopping(pulsing) the 105 Volts on and off, current flow is maintained. The end ofinjection occurs when the current supply is cut off and hydraulic pressuredrops. Therefore, fuel pressure drops rapidly in the injector.

INSTRUCTOR NOTE: This waveform may be demonstrated with a9U7330 Digital Multimeter (or equivalent) and a current probe.

STMG 672 - 43 -4/97

36

• Poppet valvemovement

POPPET VALVE MOVEMENT

0 1 2 3 4

CU

RR

EN

T

FL

OW

TIME (MILLISECONDS)

CURRENT

POPPETLIFT

5

This diagram shows that the poppet valve will open just after the ECMenergizes the solenoid. The poppet valve permits hydraulic oil to shift theinjector intensifier piston which then moves the injector plunger.

STMG 672 - 44 -4/97

37

• Timing relative to:

1. Injector currentflow

2. Poppet valvemovement

3. Injection rate

WAVEFORM AND RESPONSE CHARACTERISTICS

0 1 2 3 4

CU

RR

EN

T

FL

OW

TIME (MILLISECONDS)

CURRENT

POPPETLIFT

INJECTIONRATE

START OFINJECTION

DURATION

5

END OFINJECTION

Here timing is graphically illustrated to show:

1. The ECM initiates the signal to the injector to start injection.

2. The injector solenoid opens the poppet valve.

3. The injection rate increases.

STMG 672 - 45 -4/97

• Fuel system limits

• Variable horsepower

• Economy Shift Mode

38

FUEL SYSTEM COLD MODES

• Speed Control

• Fuel Limiting• Injection Timing• Injection Actuation Pressure• Ether Injection

Just as the MUI engine had mechanical limits to determine maximum fueldelivery during full load, full torque and acceleration, the HEUI systemalso has electronic limits to protect the engine. These limits are:

- Maximum Horsepower

- Torque Limit (Determines torque rise characteristics)

- Fuel Ratio Control (Limits fuel until sufficient boost is available)

- Cold Mode Limit (Limits fuel with cold engine to control whitesmoke)

- Cranking Limit (Limits fuel during cranking)

An acceleration delay during start-up holds the engine at low idle for twoseconds or until oil pressure reaches 140 kPa (20 psi).

Off-highway Trucks have a system which increases engine horsepower indirect drive only. This system protects the driveline from excessivetorque in the lower gears.

Off-highway Trucks also have a service tool programmable feature whichis designed to lower shift points and the fuel limit to improve fuelconsumption at the customer's request.

STMG 672 - 46 -4/97

• Cold modes

39

FUEL SYSTEM COLD MODES

• Speed Control

• Fuel Limiting• Injection Timing• Injection Actuation Pressure• Ether Injection

The HEUI fuel system is designed to modify the operationalcharacteristics of the engine during cold operation. This modification isdone to protect the environment, the engine and to improve theoperational characteristics of the engine.

INSTRUCTOR NOTE: The various Cold Modes are tabulated inServiceman's Handout No. 2. Discuss how these Cold Modevariations can change the engine characteristics, particularly duringdiagnostic operations. For example:

- Injection actuation pressure will vary with engine temperature.

- Engine speed may be raised in Cold Mode.

STMG 672 - 47 -4/97

• Fuel system derates

• Power correction

40

FUEL SYSTEM DERATES

• Automatic Altitude Compensation

• Automatic Filter Compensation

• Engine Warning Derate

As the system limits fuel for every condition, derates are also built intothe system for protection. These derates are individually covered later inthe presentation, but are summarized here:

- Automatic Altitude Compensation (Altitude derate)

- Automatic Filter Compensation (Derates for air filter restriction ifinstalled)

- Engine Warning Derate (Derates for low oil pressure and highcoolant temperature; not installed on all applications)

If a loss of boost sensor output occurs, the ECM assumes zero boostpressure. Although not strictly a derate, power is reduced byapproximately 50 to 60%.

- Fuel Temperature Compensation (Compensates up to 5% forpower loss caused by hot fuel)

➥

STMG 672 - 48 -4/97

INSTRUCTOR NOTE: This material will be reinforced if thefollowing ET tasks are demonstrated. Review the material withquestions following the tasks. The demonstration can be performedon an engine or machine with a laptop computer. The suggestedtopics are:

Basic ET review (if required)

Status screens with throttle switch status, desired engine speed,fuel position, injection actuation pressure, etc.

Active diagnostic codes

Logged diagnostic codes

Events screen

Configuration screen

Timing calibration

Injector solenoid test

Cylinder cutout

Automatic injector test

STMG 672 - 49 -4/97

41

FUEL INJECTION SYSTEM

FUEL INJECTION SYSTEM

This portion of the presentation describes the principles of operation ofthe HEUI Fuel Injection System as is used on the 3408E and 3412Eengines.

INSTRUCTOR NOTE: The various color codes which will be usedin this section of the presentation to identify flow and pressures are:

Hydraulic and Lubrication Circuits

Red - High pressure oil

Red and White Stripes - Reduced pressure oil

Brown - Lube oil pressure

Green - Lube oil suction or return

Fuel Circuits

Red - High pressure fuel

Red and White Stripes - Fuel transfer pump pressure

Green - Fuel suction or return

STMG 672 - 50 -4/97

42

PUMPCONTROL

VALVE

OILFILTER

OILCOOLER

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR


SENSORCOLD START


SENSOR

ECM

HYDRAULICSUPPLY

PUMPGROUP

COOL DOWNCIRCUIT

FUEL TANK

FUELTEMPERATURE

SENSOR

PRESSUREREGULATING

VALVE

SECONDARYFUEL

FILTER

FUELTRANSFER

PUMP

PRIMARYFUEL FILTER

WATERSEPARATOR

LUBE OILPUMP

TO LUBESYSTEM




Actuation of the fuel injection system is accomplished using hydraulics,rather than the conventional camshaft actuation commonly found on otherdiesel fuel systems.

Hydraulic actuation offers several advantages compared to mechanicalactuation, including the ability to make injection pressure independent ofengine operating speed. This capability is especially advantageous inmany respects, including transient engine response, cold starting,emissions and noise control.

INSTRUCTOR NOTE: The following schematics may appearidentical in the black and white illustrations. However, the actualslides are colored differently.

STMG 672 - 51 -4/97

• HEUI principlecomponents:


2. ECM

3. Temperaturesensor

4. Pressure sensor

5. Injector

43

12

3

54

System Components

To review, the 3400 HEUI hydraulic and fuel supply circuits contain thefollowing major components:

• Hydraulic Supply Pump Group (1) including:

- Hydraulic pump

- Fuel transfer pump

- Pump control valve

• Electronic Control Module (ECM) (2)

• Electronic Sensors (3 and 4)

- Hydraulic temperature

- Hydraulic pressure

• Injectors (5)

STMG 672 - 52 -4/97

• Hydraulic supplypump group:

1. Hydraulic pump

2. Pump control valve

3. Transfer pump

44

1

2

3

The following components are integrated into a single unit called theHydraulic Supply Pump Group:

- Hydraulic pump (1)

- Pump control valve (2)

- Transfer pump (3)

This pump group is located in the vee of the engine and is in the sameposition as the fuel injection pump on earlier engines.

Three fluid circuits are included in the system: low pressure oil, highpressure oil (hydraulic), and low pressure fuel supply.

NOTE TO THE INSTRUCTOR: These components and circuits willbe covered in detail later in the presentation.

STMG 672 - 53 -4/97

45

• Low pressure oilsupply

• Cold start reservoir

• Pressure sensor

• Temperature sensor

TO LUBESYSTEM

FUELTRANSFER

PUMP

PUMPCONTROL

VALVE

OILFILTER


OILCOOLER

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR


SENSOR

OIL PRESSURESENSOR

ECM

COOL DOWNCIRCUIT

LOW PRESSURE OIL (HYDRAULIC) SUPPLY

FUEL TANK

FUELTEMPERATURE

SENSOR

PRESSUREREGULATING

VALVE

SECONDARYFUEL

FILTERPRIMARY

FUEL FILTERWATER

SEPARATOR

LUBE OILPUMP

COLD STARTOIL

RESERVOIR

HYDRAULICSUPPLY

PUMPGROUP



System Operation

On a HEUI equipped engine, the lubrication pump has two functions:

1. Provides lubrication to the engine2. Provides low pressure charge oil to the HEUI hydraulic pump

The engine lubrication pump has been enlarged to provide the requiredincrease in flow.

The hydraulic pump has a Cold Start Oil Reservoir. This reservoirprevents the hydraulic pump from cavitating during initial enginecranking until the lubrication pump can supply adequate charge pressure.

An oil pressure sensor is located in the Cold Start Oil Reservoir, which isthe inlet to the hydraulic oil pump. The sensor monitors lubrication oilpressure. An oil temperature sensor is also installed in the reservoir. Thissensor will be referred to as the "hydraulic temperature sensor" as it isused for this purpose.

STMG 672 - 54 -4/97

46

• High pressureactuates hydraulics

TO LUBESYSTEM

FUELTRANSFER

PUMP

PUMPCONTROL

VALVE

OILFILTER


OILCOOLER

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR


SENSOR

OIL PRESSURESENSOR

HYDRAULICSUPPLY

PUMPGROUP

COOL DOWNCIRCUIT

HIGH PRESSURE HYDRAULICS

FUELTEMPERATURE

SENSOR

ECM

FUEL TANK

PRESSUREREGULATING

VALVE

SECONDARYFUEL

FILTERPRIMARY

FUEL FILTERWATER

SEPARATOR

LUBE OILPUMP

COLD STARTOIL

RESERVOIRFLUID MANIFOLD

HYDRAULIC PASSAGE


During normal operation conditions, oil is pressurized between5000 and 21500 kPa (725 and 3100 psi) by the high pressure hydraulicpump to actuate the injectors. The level of hydraulic pressure iscontrolled by the ECM, which signals the pump control valve to upstrokethe hydraulic pump.

When the engine is running, high pressure oil is available to all injectorsat all times.

Oil from the high pressure pump enters the two oil supply passages.

Reverse flow check valves are used to prevent pressure surges betweenthe oil passages on opposite banks. The oil supply passages are connectedhydraulically to the injectors by jumper tubes. Oil used by the injectors isreleased below the valve covers and drains back to the sump through thepushrod compartments.

STMG 672 - 55 -4/97

47

• Low pressure fuelsupply

• Injector cooling

TO LUBESYSTEM

FUELTRANSFER

PUMP PRESSUREREGULATING

VALVE

PUMPCONTROL

VALVE

OILFILTER


OILCOOLER

LUBE OILPUMP

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR


SENSOR

OIL PRESSURESENSOR

ECM

COOL DOWNCIRCUIT

LOW PRESSURE FUEL SUPPLY

FUELTEMPERATURE

SENSOR

FUEL TANK

SECONDARYFUEL FILTER(2 MICRON)

PRIMARYFUEL FILTER

WATERSEPARATOR

COLD STARTOIL

RESERVOIR

HYDRAULICSUPPLY

PUMPGROUP



Fuel is drawn from the tank through the water separator and the handpriming pump by a gear-type transfer pump. The fuel is then directedthrough the Electronic Control Module (ECM) housing for coolingpurposes. The fuel then flows through the secondary fuel filter.

Next, the fuel enters the low pressure supply gallery located in the fluidsupply manifolds on top of the cylinder heads. Any excess fuel notinjected leaves the manifold. The flow is then combined into one line andpasses through the pressure regulating valve, which is set between310 and 415 kPa (45 and 60 psi). From the pressure regulating valve, theexcess flow returns to the tank. The ratio of fuel between combustion andfuel returned to the tank is about 1:3 (i.e. four times the volume requiredfor combustion is supplied to the system for combustion and injectorcooling purposes).

A fuel temperature sensor is installed in the fuel supply system tocompensate for power losses caused by varying fuel temperatures.

STMG 672 - 56 -4/97

48

• Fuel and oil flow

LOW PRESSUREFUEL SUPPLY

CYLINDER HEADINJECTOR SLEEVE

FLUID SUPPLYMANIFOLD

INJECTOR

INJECTOR OILADAPTER

JUMPER TUBE

INJECTOR CLAMP

HIGH PRESSUREHYDRAULIC PASSAGE

CYLINDER HEAD

ROCKER ARM BASE

LUBE OIL PASSAGE

CYLINDER BLOCKCOOLANT

METAL WASHER

INJECTOR FLUID FLOW HIGH PRESSURE HYDRAULIC OIL

Hydraulic Unit Injector Operation

High pressure hydraulic oil is provided to each injector from the hydraulicsupply passages through individual jumper tubes.

Fuel is supplied to the injector by the low pressure supply passage locatedin the fluid manifolds (described on the next slide).

Special "Viton" o-rings are used in the hydraulic joints between theinjector and the fluid manifold.

NOTE: This slide and the following slide depart from the colorlegend by using orange for high pressure oil to avoid confusionbetween the two fluids.

STMG 672 - 57 -4/97

49

• Low pressure fuelsupply to injector

FLUID SUPPLYMANIFOLD

INJECTOR

CYLINDERHEAD

LOWER INJECTORO-RING SEAL

UPPER INJECTORO-RING SEAL

INJECTOR FUEL SUPPLY

METAL-TO- METALCONTACT

LOW PRESSUREFUEL SUPPLY


UPPER SLEEVEO-RING SEAL

LOWER SLEEVEO-RING SEAL

Low pressure fuel is supplied to the inlet of the injector through a drilledpassage located in each Fluid Supply Manifold.

The fuel supply to each injector is sealed from the combustion chamberand the area below the valve cover by upper and lower o-ring sealsbetween the injector and the cylinder head injector sleeve.

Combustion chamber gases are prevented from entering the fuel supplypassage by a metal-to-metal contact between the cylinder head injectorsleeve and the injector.

The cylinder head injector sleeve is threaded into the cylinder head. Ametal washer is used to seal the lower end of the adapter to preventleakage between the cooling system and the combustion chamber.

STMG 672 - 58 -4/97

• Fluid supply manifold

• Supply passages:

1. Hydraulic

2. Lubrication

3. Fuel

50

21 3

The following passages are located in the Fluid Supply Manifold:

- Hydraulic supply passage (1)

- Lubrication supply passage (2)

- Fuel supply passage (3)

The fluid supply manifold is mounted on the cylinder head and carriesinjector actuation hydraulic oil under pressure through the jumper tubes tothe injectors.

Low pressure fuel and lubrication oil to the valve mechanism are alsodirected through the manifold. These passages are shown in the sectionalview on the next slide.

STMG 672 - 59 -4/97

51

• Supply passages

• Additional fuel forcooling

• Fuel seals

LOW PRESSUREFUEL SUPPLY PASSAGE


HIGH PRESSUREHYDRAULIC PASSAGE

ROCKER ARMBASE

LUBRICATION OILPASSAGE

EXTRACTORSPLINES

FUEL SEALS

FLUID SUPPLY MANIFOLD

This sectional view shows the various passages in the Fluid SupplyManifold.

- High pressure hydraulic supply passages

- Low pressure fuel supply passages

- Lubrication oil supply passages

The fuel enters the front of the manifold and exits the rear. Cooling of theinjectors is achieved by circulating a larger volume of fuel past theinjectors than is required for combustion.

Initially, fuel circulates around the outside of the injector sleeve and iscontained between the sleeve and the fluid supply manifold by the upperand lower injector sleeve fuel seals.

STMG 672 - 60 -4/97

• Jumper tube and oiladaptor

52

1

2

The Jumper Tube (1) and Injector Oil Adaptor (2) direct hydraulic oilfrom the fluid manifold high pressure passage to the injector.

A specific procedure to tighten the six bolts (for the Jumper Tube andAdaptor) must be followed when installing the jumper tube. Thisprocedure follows later in the presentation.

NOTICEFailure to follow the correct tightening procedure can result in lowpower complaints caused by internal hydraulic leaks. Also, internalstrains on the injector caused by an improper tightening procedurecan cause changes in internal injector clearances which can decreaseperformance and injector life.

STMG 672 - 61 -4/97

53

• Injector currentwaveform

• Two current levels

INJECTION CURRENT WAVEFORM

0 1 2 3 4

CU

RR

EN

T

FL

OW

TIME (MILLISECONDS)

PULL-IN PEAK CURRENT

HOLD-IN PEAK CURRENT

ONE CYCLE

5

Injector Operation Characteristics

The quantity of fuel delivered is controlled by varying the time thesolenoid is energized. This period of time, called "duration," is calculatedby the ECM to ensure delivery of the correct amount of fuel. Other inputsaffect calculation of on-time, including (but not limited to) hydraulicsupply pressure, oil temperature and mapped injector performancecharacteristics. Two current levels are generated in the wave form:

1. Pull-in current is higher to create a stronger magnetic field toattract the armature and lift the injector poppet valve off its seatagainst spring force.

2. Hold-in current is used to hold the armature and poppet off itsseat. Lower current reduces heat in the solenoid and increasessolenoid life.

The injector performance map shows delivery as a function of on-time,pump pressure, and oil temperature, and is stored in the ECM memory.

STMG 672 - 62 -4/97

54

• Waveform and injectorresponse

WAVEFORM AND RESPONSE CHARACTERISTICS

0 1 2 3 4

CU

RR

EN

T

FL

OW

TIME (MILLISECONDS)

CURRENT

POPPETLIFT

INJECTIONRATE

START OFINJECTION

DURATION

5END OF

INJECTION

This slide shows that, as the ECM energizes the solenoid, the poppet valvemovement follows. Then, the injector rate increases for the start ofinjection. The end of injection occurs as the rate drops toward zero.

Therefore:

• Engine fuel timing is a function of the start of injection.

• Fuel quantity is a function of:

- The duration of injection - Injection actuation (hydraulic) pressure

➥

STMG 672 - 63 -4/97

• Pull-in current

• Poppet lift - Blue line

• Start of injection- Purple line

• Injection rate - Purple line

• End of injection

The ECM sends a higher current to the solenoid to create a strongmagnetic field. This strong field is needed to create maximum pull on thearmature, which is at its farthest distance from the solenoid.

The poppet is normally held on its inlet seat by the poppet spring. Thehigher pull-in current attracts the armature and lifts the poppet off its inletseat and toward the exhaust seat against the spring force. The ECMreduces the current level to hold-in current and the poppet is held on itsexhaust seat.

Injection starts after the exhaust seat closes and oil pressure pushes theintensifier piston and plunger down. The downward movement of theplunger pressurizes the fuel to approximately 31000 kPa (4500 psi) andthe check valve lifts, allowing fuel to enter the cylinder. The time atwhich fuel leaves the tip is called the "start of injection."

The rate at which fuel is injected is controlled by injection hydraulicpressure. Higher hydraulic pressure pushes the piston and plunger faster,causing a higher flow rate through the nozzle tip.

When the ECM ends injection, it terminates the hold-in current whichcauses the magnetic field in the solenoid to collapse. The poppet springthen moves the poppet back to the inlet seat. As the poppet travels backto the inlet seat, hydraulic oil is shut off, and the downward travel of thepiston and plunger reverses, filling the barrel for the next injectionsequence.

As pressure drops below the plunger and nozzle areas, the valve closingpressure, which is about 21000 kPa (3000 psi), causes this pressure to beretained in the nozzle for the next cycle.

INSTRUCTOR NOTE: If a disassembled or a cutaway injector isavailable, it is recommended that the preceding sequence be reviewedusing the actual components.

STMG 672 - 64 -4/97

• Major components

• Seals

55

Injector Components

The 3408E/3412E unit injector has been designed to represent the state ofthe art in the industry. This section of the presentation will describe allthe components and their functions.

This slide shows a cutaway injector and the injector sleeve. Note thefollowing major injector component groups:

- Valve body group with solenoid and poppet valve

- Barrel group with intensifier piston and plunger

- Nozzle group

The injector sleeve has four seal grooves. The two upper grooves havethe seals which contain the fuel within the fluid manifold (shown in moredetail later).

The two lower seals contain the coolant below the cylinder upper deck. Ametal washer seals the lower part of the sleeve and prevents coolant fromentering the combustion chamber.

STMG 672 - 65 -4/97

56

• Three main groups

HEUI UNIT INJECTOR

3 MAIN GROUPS

VALVE BODYGROUP

BARREL GROUP

NOZZLE GROUP

The injector consists of three basic groups which will be described indetail:

- Valve Body Group

- Barrel Group

- Nozzle Group

This view and those that follow show the exhaust port on the injectorventing the return oil downward. This condition is a modification fromthe previous design which vented the oil upward. These injectors areinterchangeable. However, the newer injector reduces the tendency of theengine to discharge oil mist from the breather.

STMG 672 - 66 -4/97

57

• Injector components

STOPPINPLUNGER SPRING SEAL BARREL BALL

DOWEL

SEAL

INTENSIFIER PISTON

RETAINER RING

WASHER

STOPPLATE

CHECKPLATE

BALL

STOP

DOWEL

SPRING

LIFTSPACER

SLEEVE

DOWEL

CHECK

TIP CASE

POPPET SPRING SLEEVE SHIM SEAL

ADAPTER BOLT

SPACER

ARMATURE

SCREW

SOLENOIDASSEMBLY

SCREW

BODYVALVE BODY GROUP

BARREL GROUP

NOZZLE GROUP

3408E/3412E HEUI INJECTORCOMPONENTS

The HEUI injector was designed with a minimum of component parts.The injector contains 35 part numbers.

This exploded view shows all the components by assemblies as follows:

The Valve Body Group contains the solenoid, armature and the poppetvalve. This assembly directs the oil to the hydraulic intensifier pistonwhich moves the fuel plunger.

The Barrel Group contains the high pressure fuel plunger.

The Nozzle Group contains the case, tip, check valve and nozzle.

NOTE: Although the injector components are explained in thispresentation, it should be noted that no individual parts of theinjector are serviced. This injector is precision assembled by amachine, and replacing individual injector components would resultin unacceptable performance problems or injector failures.

STMG 672 - 67 -4/97

58

• Injector componentparts

SHIMBARREL

PISTON

VALVE

FUEL INLETCHECK VALVE

PIN

SPACER

ADAPTER

SPACER

ARMATURE

SOLENOID

WASHER

PLUNGER

SLEEVE

SLEEVE

UNIT INJECTOR COMPONENTS

LOWER FUEL SEAL

VALVE BODY

UPPER FUEL SEAL

NOZZLE

CHECK

This slide shows the component parts in the three basic groups discussedpreviously.

The valve body has three parts (body, adaptor and spacer) which areassembled with great precision. Any damage sustained in the valve bodyarea during installation or removal will cause an injector failure.

NOTICEThe correct injector removal procedures and tooling specified in theservice manual must always be used. Any leverage applied below thevalve body can cause deformation of the poppet valve bore andpossible injector failure.

STMG 672 - 68 -4/97

59

HORIZONTALBOLTS

JUMPER TUBE

INJECTOR CLAMP

VERTICALBOLTS

INJECTOR INSTALLATIONALLEN

SCREWS

INJECTOR OILADAPTOR

Injector Removal and Installation

The correct procedures for injector removal and installation must befollowed to avoid strain on the injector and hydraulic leaks in the jumpertube area. The three mating surfaces of the jumper tube, oil adaptor andinjector must be aligned before final torque is applied.

INSTRUCTOR NOTE : At this time, it is recommended that theinjector removal and installation procedures be demonstrated.Emphasis should be placed on the use of the correct puller duringremoval (rather than a pry bar, which could result in injectordamage). Also, disassemble a used injector to identify the variouscomponents shown on this slide.

STMG 672 - 69 -4/97

• Injector assembly andinstallation

This portion of the assembly procedure ensures that all mating and sealingfaces are flush and in complete contact before tightening the bolts.

1. Clean the faces of the injector and the injector sleeve and installnew o-rings.

2. Lubricate the o-rings with oil and insert the injector in the injectorsleeve.

3. Visually align the injector with the flat surface parallel to thecenterline of the engine.

4. Position the injector clamp on the injector and tighten the bolt to 47 ± 9 N•m (35 ± 7 lb. ft.).

5. Install new seals on the jumper tube and rocker arm base.

6. Place the injector oil adaptor and jumper tube in position.

7. Install the allen screws and hex head bolts finger tight. If theinjector oil adaptor was previously installed on the injector, loosenthe allen screws.

The objective at this point in the procedure is to bring all the mating facesinto complete contact and alignment before starting the final torqueprocedure.

Failure to align the components will put a strain on the injector which willthen distort the poppet valve and barrel bores. These components operatewith a clearance of 5 microns because of the high injection and hydraulicpressures. Therefore, even a small amount of distortion will cause aseizure.

Additionally, some misalignment could cause combustion gases to enterthe supply system.

STMG 672 - 70 -4/97

• Injector installationtorque sequence

After all the mating surfaces are aligned, the torquing procedure can beperformed:

1. Tighten the allen screws and hex head bolts finger tight or justsufficiently to bring the mating surfaces together and intoalignment.

2. Apply an initial torque to the vertical hex head bolts of 5 ± 3 N•m(4 ± 2 lb. ft.).

3. Apply an initial torque to the horizontal hex head bolts of 5 ± 3 N•m (4 ± 2 lb. ft.).

4. Apply an initial torque to the allen screws of 1 ± 0.2 N•m (10 ± 2 lb. in.).

5. Final torque the vertical hex head bolts to 47 ± 9 N•m (35 ± 7 lb. ft.).

6. Final torque the horizontal hex head bolts to 47 ± 9 N•m (35 ± 7 lb. ft.).

7. Final torque the allen screws to 12 ± 3 N•m (9 ± 2 lb. ft.).

8. Check the system for leaks (crank with injection disabled). Then,check the hydraulic pressure (compare with desired pressure).

A number of possibilities for leaks can exist. Oil under high pressure mayleak from the jumper tube joints or from the injector valve body exhaustport. Fuel could leak from the upper seal on the injector. Also,combustion gas can possibly leak from the base of the injector.

If air has entered the fuel supply system, multiple injectors on one bankmay malfunction. If the above procedure was not followed, air couldenter past the lower o-ring seal. If this condition occurs, remove theinjector and check for carbon below the lower o-ring seal. Replace theseal and perform the torque sequence.

Air in the system may be detected by lightly touching the flexible returnline and checking for extreme pulsations or pressure spikes felt throughthe line. As an alternative, install a sight glass in each return line, run theengine and check for air.

Combustion gas leakage will usually affect the injector with the leakfollowed by the injectors downstream (toward the rear) of the leak.

In conclusion, the system is reliable. However, failure to follow theseprocedures may cause malfunctions.

STMG 672 - 71 -4/97

60

• Solenoid de-energized

• Solenoid energized

• Oil flows to intensifierpiston

SOLENOID DE-ENERGIZED SOLENOID ENERGIZEDPOPPET VALVE CLOSED POPPET VALVE OPEN

ARMATURESCREWPOPPET

SPRINGINLET

VALVE SEAT

SOLENOID

POPPET VALVE

ARMATURE

EXHAUSTVALVE SEAT

VALVE BODY GROUP

Injection Sequence

When the solenoid is de-energized, the poppet valve is held on its inlet(left) seat by the poppet spring. The poppet valve is connected to thearmature by the armature screw. When the poppet is closed, the inlet seatprevents high pressure oil from entering the injector. The exhaust poppetseat is open, connecting the intensifier piston cavity to the atmosphere.

Based on input signals from the various electronic sensors, the ECMcalculates the quantity and timing of fuel to be delivered by the injector tothe combustion chamber. At the appropriate time, the ECM sends anelectrical current to the injector solenoid.

The solenoid develops a magnetic force which attracts the armature andshifts the poppet valve. The poppet valve moves against the spring force,opens the inlet seat and closes the exhaust (right) seat. Hydraulic pressureoil from the supply manifold is directed through the jumper tube to the topof the intensifier piston.

STMG 672 - 72 -4/97

61

• Plunger moves down

• Pressurizes fuel belowplunger

• Pressureintensification


INTENSIFIERPISTON

PLUNGER

FUEL TONOZZLE

BARREL

BARREL GROUPFUEL PRESSURE INCREASE

REVERSE FLOWCHECK VALVE

FUEL FROMTRANSFER PUMP

SUPPLY OIL

Supply oil flow from the poppet valve causes the intensifier piston and thefuel plunger to move downward. The displacement of the plungerpressurizes the fuel trapped between the plunger face and the nozzle checkseat.

NOTE: The intensifier piston has almost seven times the area of thefuel plunger. When the hydraulic circuit is supplying a pressure of21000 kPa (3000 psi), approximately 145000 kPa (21000 psi) will begenerated below the fuel plunger.

STMG 672 - 73 -4/97

62

• Fuel atomization

VIEW OF STOP PLATE & REVERSE FLOW CHECK VALVE


FUEL ATOMIZATION

NOZZLE GROUP

CHECK VALVE

When the trapped pressure exceeds the nozzle valve opening pressure(VOP), typically 31000 kPa (4500 psi), the check valve lifts, and fuelflows through the holes in the nozzle into the combustion chamber. At theend of injection, the nozzle check valve closes at approximately21000 kPa (3000 psi).

The reverse flow check valve is used to prevent combustion induced gasflow from entering the nozzle area.

The nozzle of the injector is very similar to the EUI unit injector. Sixorifices, each with a diameter of 0.252 mm (.010 in.), are arranged at anangle of 140 degrees.

STMG 672 - 74 -4/97

63


• Solenoid de-energized

• Poppet valve closes

INLETVALVE SEAT

SOLENOID

POPPET VALVE

ARMATURE

EXHAUSTVALVE SEAT

SOLENOID DE-ENERGIZED

VALVE BODY GROUP

The end of injection is accomplished by shutting off the current from theECM to the injector solenoid. The resulting loss of magnetic force on thearmature allows the return spring force to shift the poppet valve off theexhaust seat.

The poppet returns to the inlet seat in the valve body, blocks the flow fromthe hydraulic oil supply, and simultaneously fully opens the exhaust valveseat. This action vents the injector internal hydraulic circuit below thevalve cover.

STMG 672 - 75 -4/97

64


• Intensifier pistonmoves up

• Nozzle check valvecloses

SHIM

BARREL

PISTON

VALVE

BALL

PIN

SPACER

ADAPTER

SPACER

ARMATURE

SOLENOID

WASHER

PLUNGER

SLEEVE

SLEEVE

NOZZLE

BODY

UNIT INJECTOREND OF INJECTION

CHECK

When vented, the intensifier piston and fuel plunger are pushed upwardby the plunger return spring force until the intensifier piston contacts thevalve body. This upward displacement of the intensifier piston ventsspent oil from the injector below the valve cover.

Retraction of the fuel plunger decreases the pressure in the fuel chamberbelow the plunger, which permits the nozzle check valve to close whenthe pressure in the nozzle drops below the valve closing pressure (VCP)of approximately 21000 kPa (3000 psi).

STMG 672 - 76 -4/97

65

• Barrel refilling

BARREL GROUPREFILLING THE BARREL

BARREL

PISTON


PIN

SPACER

WASHER

PLUNGER

SLEEVE

NOZZLE

NOZZLE CHECKVALVE

FUEL EDGEFILTER

As the plunger continues to retract, the pressure below the plungerdecreases below the fuel supply gallery pressure. The fuel inlet checkvalve then opens, allowing fuel to pass through the edge filter (next slide)to the supply gallery to refill the injector for the next injection sequence.

STMG 672 - 77 -4/97

66

• Fuel edge filter


EDGE FILTER

EDGE FILTER


FUEL INLET FUEL INLET

Note the location of the fuel edge filter. The edge filter is formed by twoflat parallel surfaces that are approximately 130 microns apart. Thesesurfaces trap and break down particles which might be big enough to plugthe nozzle orifices.

STMG 672 - 78 -4/97

67

• Injection rate shaping

• Low emission levels

• PRIME

PRIME INJECTION RATE SHAPING

0 1 2 3 4TIME (MILLISECONDS)

5

PRIME = PRE-INJECTION METERING INJECTION RATE

DURATIONSTART OF INJECTION

Another feature used in the injector for 3408E/3412E applications is aninjection rate shaping device. Rate shaping refers to tailoring the way fuelis delivered to the engine to obtain a desirable result. In the 3408E/3412Eapplication, rate shaping reduces the quantity of fuel delivered to thecombustion chamber during the ignition delay period (i.e. the timebetween the start of injection and start of combustion) to levels whichproduce low engine combustion noise and low emissions.

The device used to create rate shaping is known as PRIME, anabbreviation for PRe-Injection MEtering. This device is basically acontrolled spill port which serves to limit the amount of fuel delivered tothe combustion chamber during the initial 25% displacement of the fuelplunger. This metering action produces the desired reduction of fueldelivery during the ignition delay period.

STMG 672 - 79 -4/97

68

• Injection rate shaping

1. Start of injection

2. Pressure drop

3. Final increase

• Benefits

CROSS SECTIONOF PLUNGER

PRIME RATESHAPING PASSAGE

PLUNGER

BARREL

SPILLPORT

FUEL TONOZZLE GROUP

START OF INJECTION PRESSURE DROPFINAL

PRESSURE INCREASE

BARREL GROUPPRIME RATE SHAPINGOIL FLOW

This slide shows the three stages in PRIME rate shaping.

1. Injection pressure starts to increase and causes the initialmovement of the plunger.

2. When the prime rate shaping passage on the plunger is passing thespill port in the barrel, pressure decreases below VCP aspressurized fuel leaks through the passage in the plunger into thespill port. At this time, nozzle flow momentarily decreases.

3. As the plunger continues downward, the PRIME rate passagepasses the spill port and pressure will again increase, causinginjection to resume.

This feature reduces emissions, smoke and noise. It also provides asmoother combustion cycle and reduces wear on the cylinder components.

STMG 672 - 80 -4/97

69

• Internal leakage

• Fluids are vented topump inlet

BARREL GROUPVENTING INTERNAL LEAKS

INTENSIFIERPISTON SEAL

VENTINGCHECK VALVE

BARREL

INTENSIFIERPISTON

During the normal injection cycle, the pressure of the oil supplied to thetop of the intensifier piston can increase to 22800 kPa (3300 psi). A sealis installed to minimize leakage past the piston.

Some oil which is necessary for lubrication of the intensifier piston maypass the seal and settle momentarily below the piston.

Also, a small amount of fuel may leak past the plunger and barrel. Thisfuel will settle momentarily in the cavity below the intensifier piston.

If the fluids which accumulate below the piston are not vented, ahydraulic lock could occur. As the piston moves down, the fuel is ejectedpast the barrel ball check valve to the low pressure inlet. The check valvethen closes during the plunger and piston upstroke.

STMG 672 - 81 -4/97

70

• Injector check valves:

- Fuel inlet

- Barrel

- Reverse flow

- Nozzle

BARREL GROUP NOZZLE GROUPFUEL INLETCHECK VALVE

NOZZLECHECK VALVE

FUELATOMIZATION

VENTINGCHECK VALVE


INJECTOR CHECK VALVES

Four check valves are installed in the injector. Three check valves areinstalled in the Barrel Group and one is installed in the Nozzle Group.

The Fuel Inlet Check Valve allows fuel to fill the barrel below the plunger,but closes as the plunger moves down and pressure increases.

The Venting Check Valve vents fluids from below the intensifier piston.

The Reverse Flow Check Valve prevents combustion gasses from flowingback through the injector from the nozzle.

The Nozzle Check Valve controls valve opening pressure by preventingthe flow of fuel through the nozzle holes until sufficient pressure isavailable to lift the valve from its seat.

STMG 672 - 82 -4/97

71

• Hydraulic pressurecontrol

IDLE PEAK TORQUE RATED

INJE

CT

ION

PR

ES

SU

RE

MECHANICALLY ACTUATEDFUEL SYSTEM

HEUI

ENGINE SPEED

HYDRAULIC INJECTION PRESSURE CONTROL

HYDRAULIC SYSTEM

The desired hydraulic actuation pressure for fuel injection can becontrolled independent of engine speed.

Many combinations of on-time and hydraulic operating pressure existwhich can result in a specific quantity of fuel per injector stroke beingdelivered to the combustion chamber. This characteristic is useful whentuning the engine to optimize performance, response, emissions, and otherparameters.

This feature makes the HEUI system superior; injection pressure canreach its maximum value regardless of engine speed. Maximum injectionpressure is normally required at full torque speed. This characteristiccontrasts with pump and line systems where pressure is proportional toengine speed.

STMG 672 - 83 -4/97

• Variable displacementpiston pump

• Cold start oil reservoir

• Serviceable parts

72

Hydraulic Supply Pump Group

The 3408E/3412E Hydraulic Supply Pump Group is a variabledisplacement, axial piston pump similar to those used in many machinehydraulic systems.

The pump features a nine piston rotating group and variable displacementcontrol. The pump is driven by the engine timing gears at 1.167 timesengine speed and produces 59 L/min. (15.5 gpm) at rated engine speed.

Low pressure oil from the engine lubricating pump is supplied to the inletof the pump Cold Start Oil Reservoir. The purpose of the reservoir is tokeep the system primed during cool down. During cold startingconditions, this volume of oil helps to shorten start times.

The lubrication system oil pressure and hydraulic temperature sensors arelocated in the reservoir.

The Hydraulic Supply Pump Group contains the following serviceableparts:

- Transfer Pump

- Reverse Flow Check Valves

- Pump Control Valve

- Compensator Valve Block

STMG 672 - 84 -4/97

• Hydraulic supplypump mountingadapter

1. Pump drive splines

2. Alignment bolt hole

3. Atmosphericpressure sensorlocation

73

2

3

1

The Hydraulic Supply Pump group is mounted on the adapter shown onthe slide. The pump drive shaft engages in the drive splines (1).

A large bolt is installed in the hole (2) in the adaptor base to provide goodalignment between the adaptor and the engine block.

Note the location of the Atmospheric Pressure Sensor (3) in the housing.The Atmospheric Pressure sensor is vented to the atmosphere below thehousing. The housing contains a foam plug to prevent the entry of dirtinto the sensor.

STMG 672 - 85 -4/97

74

• Pump priming

• Priming port

• Case drain orifice

• Priming procedure

PRIMING PORT

ORIFICE

RESERVOIR

SWASHPLATE

TRANSFER PUMP

COMPENSATORVALVE

HEUI PUMP

VALVE BASE

DRAIN PASSAGE

Priming the pump after replacement is extremely important to preventslipper pad overheating. Pump failure or damage will occur due to lack oflubrication if the case is not filled during replacement.

The priming port is located adjacent to the inlet tube (not shown) and isthe rearmost of the two plugs. The front plug is the case drain passageand is vented over the pump drive gears. Therefore, the front plug cannotbe used for priming.

A .50 mm (.020 in.) orifice is located between the fill port line and thecase drain line. This orifice allows a continuous flow from the case to thedrain circuit for lubrication, cooling and venting of air from the reservoir.

The procedure to prime the Hydraulic Supply Pump case is:

1. Remove the plug from the priming port. 2. Fill the compartment with oil and replace the plug. 3. Fill the reservoir with oil (if the machine is not equipped with

pre-lube).

STMG 672 - 86 -4/97

• Fuel transfer pump(arrow)

75

The fuel transfer pump (arrow) is driven by a coupling that connects theend of the high pressure supply pump drive shaft to the transfer pumpinput shaft.

This gear pump has an integral relief valve set to open at 620 to 760 kPa(90 to 110 psi). This valve does not normally operate because thepressure regulating valve (next slide) is controlling the pressure.

Fuel is drawn from the tank to the combined primary fuel filter/waterseparator. The fuel then passes through the ECM and the secondary fuelfilter to the fluid manifold and the injectors.

STMG 672 - 87 -4/97

• Pressure regulatingvalve

• Fuel pressure testplug (arrow)

76

Fuel system pressure is controlled by the Pressure Regulating Valve. Thisvalve regulates pressure between 310 to 415 kPa (45 to 60 psi).

The valve is located downstream of the fluid manifold fuel passages andthe injectors. Fuel which passes through the valve is returned to the fueltank.

The fuel lines from both fuel passages in the manifolds are joined at theregulating valve.

Fuel pressure can be checked by removing the plug (arrow) andconnecting a gauge.

STMG 672 - 88 -4/97

77

• Cold start oil reservoir

• Reverse flow checkvalves

TO LUBESYSTEM

FUELTRANSFER

PUMP

PUMPCONTROL

VALVE

OILFILTER

OILCOOLER

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR


SENSOR

OIL PRESSURESENSOR

ECM

COOL DOWNCIRCUIT

COOL DOWN BYPASS CIRCUIT

FUEL TANK

FUELTEMPERATURE

SENSOR

PRESSUREREGULATING

VALVE

SECONDARYFUEL

FILTER

LUBE OILPUMP

PRIMARYFUEL FILTER

WATERSEPARATOR


HYDRAULICSUPPLY

PUMPGROUP

COLD STARTOIL

RESERVOIRFLUID MANIFOLD

HYDRAULIC PASSAGE

DRAIN

.020 IN.ORIFICE

The Cold Start Oil Reservoir is located above the Hydraulic Supply PumpGroup. The Hydraulic (Oil) Temperature and Lube Oil Pressure Sensorsare located at the top of the reservoir.

When the engine is shut down and oil in the supply manifolds cools andcontracts, oil from the reservoir flows through the cool down circuit to themanifolds. This design prevents the formation of air bubbles in thehydraulic supply manifolds during cooling to provide fast starting andsmooth running. A 0.50 mm (.020 in.) drilled passage in the reservoirallows the air to be vented through the case drain after start-up.

The Reverse Flow Check Valves prevent hydraulic surges between the oilsupply passages and are used to maintain stable pressures. The valves areshown on the next slide.

STMG 672 - 89 -4/97

• Reverse flow checkvalves (arrows)

78

This view shows the rear of the hydraulic supply pump with theaftercooler removed from the engine.

The Reverse Flow Check Valves (arrows) are located at the rear of thepump group to the right of the transfer pump. The high pressure lines tothe manifolds are connected to the check valves.

STMG 672 - 90 -4/97

79

• Reverse flow checkvalve

• Check valves blockpressure surges frominjectors

CHECKFITTING SPRINGVALVE BLOCK SEAT

REVERSE FLOW CHECK VALVE

FROMPUMP

TOINJECTORS

SEAT(END VIEW)

The hydraulic supply pump group has two outlet ports, each connected bysteel tubes to a hydraulic supply manifold. An integral reverse flow checkvalve is located in each outlet port.

This view shows that pressure surges travelling back from the injectorstoward the pump will cause the check valve to close and block anyinterference between the banks. In normal operation, the valve willoscillate at high frequency as it blocks the pressure surges.

The valve check fits loosely on the shaft to allow oil flow from thereservoir during the cooling process.

If the check valves were not in the system, pressure surges between thebanks would cause erratic operation of the injectors by adversely affectingtiming. The pressure surge causes the poppet valves to open prematurely.This condition would start

fuel injection earlier than normal, thereby advancing the timing.

STMG 672 - 91 -4/97

• Pump components:

1. Cold start reservoir

2. Swashplate

3. Swashplate pivot

4. Displacementcontrol piston

5. Pump piston

6. Check valves

80

65

42

3

1

This cutaway view of the Hydraulic Supply Pump Group shows thefollowing components:

Cold Start Oil Reservoir (1)

Swashplate (2)

Swashplate Pivot (3)

Displacement Control Piston (4)

Pump Pistons (5, one of seven shown)

Check Valves (6)

STMG 672 - 92 -4/97

• Valve components:

1. Compensator valveassembly

2. Pressure limiterspool

3. Load sensingspool

4. Check valve

5. Valve base

• Oil passages:

6. Oil supply frompump

7. Pressure limiter tocase drain

8. To displacementcontrol piston

9. Pump control valveto case drain

• Pump components:

10. Transfer pumpdrive and mounting

11. Pump control valve

81

2

10

9

1

4

6

11

3

7

8

5

This cutaway view shows the compensator valve assembly and the pumpcontrol valve. Note the following components which will be referred toin the presentation:

Compensator Valve Assembly (1)

Pressure Limiter Spool (2)

Load Sensing Spool (3)

Check Valve (4)

Valve base (5)

Oil Passages:

Oil supply from pump (6)

Pressure Limiter to Case Drain (7)

To Displacement Control Piston (8)

Pump Control Valve to Case Drain (9)

Transfer Pump Drive and Mounting (10)

Pump Control Valve (11)

INSTRUCTOR NOTE: The Compensator Valve is an emissionsdevice and should not be adjusted.

STMG 672 - 93 -4/97

82

• Hydraulic supplypump circuit

TO LUBESYSTEM

PUMPCONTROL

VALVE

OILFILTER

3408E/3412E HEUI FUEL SYSTEM HYDRAULIC SYSTEM OPERATION

OILCOOLER

LUBE OILPUMP

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR


SENSOR

OIL PRESSURESENSOR

HYDRAULICSUPPLY

PUMPGROUP

COOL DOWNCIRCUIT

FUEL TANK

FUELTEMPERATURE

SENSOR

PRESSUREREGULATING

VALVE

SECONDARYFUEL

FILTER

FUELTRANSFER

PUMP


COLD STARTOIL

RESERVOIR

PRIMARYFUEL

FILTER

ECM


System Operation

As stated earlier, the Hydraulic Supply Pump Group combines thefunctions of the high pressure oil pump, the fuel transfer pump, and thepump control valve into a single unit. The function of the HydraulicSupply Pump Group is to provide the required oil flow at the desiredpressure to operate the injectors, provide the supply of low pressure fuelrequired for refilling the injectors after each injection, and for ECMcooling.

As the oil is supplied by the pump rotating group, the pressure is raisedfrom the reservoir level of approximately 415 kPa (60 psi) to the pressurerequired for injector operation. Depending on the engine rating, theoperating conditions, and the engine mapping characteristics, this pressureis controlled between 5000 and 22800 kPa (725 and 3300 psi).

STMG 672 - 94 -4/97

83

• Conditions duringSTART-UP

• Displacement variedby changingswashplate angle

• Swashplate at fulldisplacement duringstart-up

• Pump control valvesolenoid energized

TO LUBESYSTEM

TO RIGHT OILMANIFOLD

TO LEFT OILMANIFOLD

COLD STARTRESERVIOR

OIL SUMPPUMP

CONTROLVALVE

LOADSENSINGSPOOL

PRESSURELIMITERSPOOL

PUMPCASE DRAIN

SOLENOID(ENERGIZED)

DISPLACEMENTCONTROL PISTON

HEUI HYDRAULIC CONTROL SYSTEMSTART-UP

CHECK VALVE

SUPPLY PUMP

The displacement of the pump is controlled to maintain the desiredoperating pressure at the flow rate required by the injectors. Thedisplacement is regulated by an electro-hydraulic control.

Displacement of the pump is varied by pivoting the swashplate from 0 degrees to a maximum angle of 15.5 degrees. When the engine is notrunning, the swashplate is at the maximum angle. During operation, thedisplacement control piston adjusts the swashplate position to meet thesystem flow demand.

During initial cranking, the swashplate is at full displacement until thesupply pressure increases to 6200 kPa (900 psi). The spring at the end ofthe load sensing spool regulates this pressure. Then, the specificationprogrammed into the ECM for normal cranking will override thispressure. Until this point, the control valve solenoid is fully energized forthe pressure increase.

STMG 672 - 95 -4/97

84

• Compensator valveconditions duringSTART-UP

• Displacement controlpiston vented to casedrain

PRESSURE LIMITER SPOOL

CHECK VALVE

PUMP CONTROLVALVE

DRAIN ORIFICE

ORIFICE

TOCASEDRAIN

LOAD SENSING SPOOL

FROM DISPLACEMENTCONTROL PISTON

REVERSE FLOWCHECK VALVES

START-UPCOMPENSATOR ASSEMBLY

TO CASE DRAIN

During START-UP, pressure from the pump enters the compensatorassembly. The Pump Control Valve is energized for quick pressurebuild-up.

Pressure is felt at both ends of the Load Sensing Spool. The spool isshifted to the right and oil from the Displacement Control Piston is ventedto case drain. The swashplate is at maximum angle.

The drain orifice below the Pump Control Valve provides a small amountof restriction to improve valve stability.

STMG 672 - 96 -4/97

85

• Conditions duringDESTROKE

• Pump control valvesolenoid de-energized

• Pump control valvechanges pumpdisplacement

TO LUBESYSTEM


TO LEFT OILMANIFOLD

COLD STARTRESERVIOR

OIL SUMPPUMP

CONTROLVALVE

LOADSENSINGSPOOL


PUMPCASE DRAIN

SOLENOID(DE-ENERGIZED)

HEUI HYDRAULIC CONTROL SYSTEMDESTROKE

CHECK VALVE


SUPPLY PUMP

After the engine starts and pressure increases, the ECM will signal thecontrol valve to match the actual with the desired pressure bymomentarily de-energizing and then regulating the current flow to thepump control valve solenoid.

The decrease in current applied to the pump control valve solenoid lowersthe pressure required to initiate flow through the pump control valve.This lower cracking pressure on the pump control valve creates a forceimbalance on the load sensing spool, causing the spool to move towardthe spring end of the compensator. This spool motion connects thedisplacement control piston to pump output flow, allowing the swashplateto decrease the displacement of the pump. The decreased displacementlowers the pump output to the pressure level required by the ECM.

STMG 672 - 97 -4/97

86

• Compensator valveconditions duringDESTROKE

• Displacement controlpiston pressurized

PUMPCONTROL VALVE

DRAIN ORIFICETO DISPLACEMENT CONTROL PISTON

TO CASE DRAIN

PRESSURELIMITER SPOOL

CHECK VALVE

ORIFICE

LOAD SENSINGSPOOL

DESTROKECOMPENSATOR ASSEMBLY

During DESTROKE, the ECM momentarily de-energizes the PumpControl Valve causing a pressure drop in the spring chamber of the LoadSensing Spool.

Unbalanced pressures force the spool to the left, allowing the oil to enterthe Displacement Control Piston and move the swashplate towardminimum angle.

STMG 672 - 98 -4/97

87

• Conditions duringUPSTROKE

• Pump control valveenergized

TO LUBESYSTEM


TO LEFT OILMANIFOLD

COLD STARTRESERVIOR

OIL SUMPPUMP

CONTROLVALVE

LOADSENSINGSPOOL


PUMPCASE DRAIN

SOLENOID(ENERGIZED)

HEUI HYDRAULIC CONTROL SYSTEMUPSTROKE

CHECK VALVE


SUPPLY PUMP

As the load on the engine increases and higher pressure is required, theECM will signal the control valve to increase pressure by increasing thecurrent flow to the pump control valve solenoid.

The increase in current applied to the pump control valve solenoid raisesthe pressure setting of the pump control valve. This higher pressure at thepump control valve creates a force imbalance on the load sensing spool,causing the spool to move toward the supply signal line end of thecompensator. This spool motion vents the displacement control piston tocase drain, allowing the spring to move the swashplate to increase thedisplacement of the pump. The increased displacement raises the pumpoutput to the desired pressure level required by the ECM.

STMG 672 - 99 -4/97

88

• Compensator valvepositions duringUPSTROKE

• Displacement controlpiston is drained

PRESSURELIMITER SPOOL

CHECK VALVE

ORIFICE

LOAD SENSINGSPOOL

PUMPCONTROL VALVE

DRAIN ORIFICE

FROMDISPLACEMENT

CONTROL PISTON

TO CASE DRAIN

UPSTROKE

COMPENSATOR ASSEMBLY

As the load is applied to the engine, the ECM increases current to thePump Control Valve.

Pressure is felt at both ends of the Load Sensing Spool. The spool movesto the right (due to spring force) and oil from the Displacement ControlPiston is vented to case drain, which allows the swashplate tomomentarily go to maximum angle and build pressure quickly.

STMG 672 - 100 -4/97

89

• Pressure limiteroperation

• Check engine lampindicates the fault

• Pump control valvetest

TO LUBESYSTEM


TO LEFT OILMANIFOLD

COLD STARTRESERVIOR

OIL SUMPPUMP

CONTROLVALVE

LOADSENSINGSPOOL


PUMPCASE DRAIN

SOLENOID(DE-ENERGIZED)

HEUI HYDRAULIC CONTROL SYSTEMPRESSURE LIMITER OPERATION


SUPPLY PUMP

PLUGGEDORIFICE

If the load sensing spool or pump control valve sticks or otherwisemalfunctions to create higher than desired operating pressures, themaximum pressure limiter spool is utilized. In this schematic, a pluggedorifice is simulated. (This example represents an actual condition whichwas caused by debris being introduced during a field replacement of thecompensator valve.)

The Pressure Limiter Spool directs pump outlet flow to the displacementcontrol piston and reduces the stroke of the pump if the system pressureexceeds 25600 kPa (3700 psi).

During these conditions, the pump will develop 24800 to 25600 kPa(3600 to 3700 psi) maximum pressure, regardless of the desired hydraulicpressure. The Check Engine Lamp will be ON, indicating a fault.

A Pump Control Valve Test will verify the control valve operation. Thistest enables the technician to manually ramp the pressure up and downusing the ET service tool. This procedure will also be useful whenevaluating the condition of the hydraulic system.

STMG 672 - 101 -4/97

90

• Pressure limiteroperation

• Pressure limiterdirects pressure tocontrol piston

PRESSURE LIMITERSPOOL

CHECK VALVE

ORIFICE

LOAD SENSINGSPOOL

PUMPCONTROL VALVE

DRAIN ORIFICE

TODISPLACEMENT

CONTROL PISTON

TO CASE DRAIN

PLUGGEDORIFICE

PRESSURE LIMITER OPERATION

COMPENSATOR ASSEMBLY

If the supply pressure exceeds 25600 kPa (3700 psi), the force acts on thePressure Limiter Spool and shifts it to the left. This movementcompresses the spring and allows oil to unseat the check valve andpressurize the displacement control piston. The swashplate moves tominimum angle to decrease flow and limit system pressure.

STMG 672 - 102 -4/97

91

• Pump control valve

• Flow controlled bycompensator andpump control valve

ADAPTER CAGE

RINGSHELLPIN

STATOR

SEAL SEATPOPPETVALVE

SOLENOIDARMATURE

STOP

TOCASE DRAIN

FROM LOADSENSING SPOOL

VALVE

VALVEBLOCK

NO CURRENT FLOW

COILASSEMBLY

PUMP CONTROL VALVE

EDGE FILTER

SPRINGRETAINER

The pump control valve is mounted on the compensator control assemblywhich contains the load sensing spool and the pressure limiter. In thisslide, the pump control valve is open, allowing pressure to vent to casedrain.

Flow to and from the displacement control piston is determined by thecompensator control assembly and the pump control valve. Thecompensator control assembly senses pump output pressure through apilot pressure signal line. The pump control valve varies the pressure tothe displacement control piston by varying the pressure on one end of theload sensing spool valve.

The load sensing spool directs oil to and from the displacement controlpiston. The spool has a hole through its center, which allows pilotpressure to reach both ends of the spool. The spring force on the loadsensing spool is adjusted at the factory. The pump will develop 5000 kPa(725 psi) with the pump control solenoid valve disconnected whilecranking the engine with the injectors disabled.

STMG 672 - 103 -4/97

92


• High current flowequals high pressure

ADAPTER CAGE

RINGSHELLPIN

STATOR

SEAL SEATPOPPETVALVE

SOLENOIDARMATURE

STOP

CASE DRAINVALVEBLOCK

COILASSEMBLY

HIGH CURRENT FLOW

PUMP CONTROL VALVE

EDGE FILTER

SPRINGRETAINER

FROM LOADSENSING SPOOL

VALVE

The pressure level in the hydraulic operating supply is monitored by ahydraulic pressure sensor. When the hydraulic pressure is less thandesired (as determined by the ECM), the current level applied to the pumpcontrol valve solenoid is increased.

The increase in current to the solenoid raises the pressure required toinitiate flow through the pump control valve. This higher crackingpressure for the pump control valve creates a force imbalance on the loadsensing spool, causing the load sensing spool to move toward the supplysignal line end of the spool. This spool motion vents the displacementcontrol piston to pump case drain, allowing the swashplate to increasedisplacement of the pump.

The increased displacement raises the hydraulic output to the rate requiredby the ECM for the injectors.

➥

STMG 672 - 104 -4/97

INSTRUCTOR NOTE: To reinforce this presentation, the followingtasks may be demonstrated on an engine:

Hydraulic pump priming

Remove and install a pump control valve and the compensatorvalve assembly.

Check the following using the status screen:

- Desired hydraulic pressure

- System hydraulic oil pressure

- System hydraulic oil temperature

- Percentage current to pump control valve

Using the ET Injection Actuation Pressure Test, check the pumpand pump control valve operation, and check for correctpressures throughout the range.

Physically check for leaks externally and internally below thevalve covers (injectors must be disabled during cranking with thevalve covers removed).

STMG 672 - 105 -4/97

• Six system powersupplies

93

HEUI SYSTEM POWER SUPPLIES

• ECM: 24 VOLTS

• INJECTORS: 105 VOLTS

• ANALOG SENSORS: 5 VOLTS

• SPEED/TIMING SENSORS: 12.5 VOLTS

• DIGITAL SENSORS: 8 VOLTS

• PUMP CONTROL VALVE: 0 to 24 VOLTS

SYSTEM POWER SUPPLIES

The HEUI system has six power supplies with various voltages as shown.

EXTERNAL POWER SUPPLY

ECM power supply 24 Volts

INTERNAL POWER SUPPLIES

Speed/Timing Sensor power supply 12.5 Volts

Injector power supply 105 Volts

Analog Sensor power supply 5 Volts

Digital Sensor power supply 8 Volts

Pump Control Valve power supply 0 to 24 Volts

The power supplies are described in detail in the following section.

STMG 672 - 106 -4/97

94

• 24-Volt power supply

• Power supplycomponents

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH





24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS

PUMPCONTROL VALVE



OIL PRESSURE SENSOR



COOLANT FLOW SWITCH

8 OR 12INJECTORS


INSTRUMENTPANEL




CAT DATA LINK

FAN

FAN SPEED SENSOR

FAN CONTROL VALVE



THROTTLESENSOR

ACCELERATORPEDAL

DISCONNECT SWITCH

3408E/3412E HEUI SYSTEMECM POWER SUPPLY COMPONENTS

MACHINEHARNESS

ECM Power Supply

The power supply to the ECM and the system is drawn from the 24-Voltmachine battery. The principle components in this circuit are:

- Battery- Key Start Switch- Main Power Relay- 15 Amp Breaker- Ground Bolt- ECM Connector (P1/JI)- Machine Interface Connector (J3/P3)

If the supply voltage exceeds 32.5 Volts or is less than 9.0 Volts, adiagnostic code is logged. (See the Troubleshooting Guide for completedetails on voltage event logging.)

NOTE: The ground bolt is the only power supply componentmounted on the engine.

STMG 672 - 107 -4/97

95

• ECM power supplycircuit

0511040623

ECM(3408E/3412E)

(-) BATTERY(-) BATTERY(+) BATTERY(+) BATTERYKEY SWITCH ON

229-BK-14229-BK-14150-RD-14150-RD-14113-OR

12

26

24 VOLTS DC

(+)

(-)

ENGINE BLOCKGROUND BOLT

CIRCUIT BREAKER

BATTERY

R

C

SB ST

OFFON

308-YL

200-BK

105-RD

KEY SWITCH

112-PU

117-RD

113-OR

15 A

10 AMPP3 J3

P1 J1

ECM POWER SUPPLY CIRCUIT

DISCONNECTSWITCH

This schematic shows the principle components for a typical powersupply circuit. Battery voltage is normally connected to the ECM.However, an input from the key start switch turns the ECM on.

The machine wiring harness can be bypassed for troubleshootingpurposes. These steps are described in the Troubleshooting Procedure.

The supply Voltage may be checked using the ET Status Screen display.

NOTE: The power supply cables are paired to reduce resistance.

STMG 672 - 108 -4/97

96

• 12.5-Volt powersupply

393229381812

732-PK996-GN998-BR999-WHF723-PKF724-PU


ECM(3408E/3412E)

P2 J2

ABC

ORBKWH

SECONDARYSPEED/TIMINGSENSOR (LH)

ABC

ORBKWH

PRIMARYSPEED/TIMINGSENSOR (RH)

SPEED/TIMING SENSOR POWER SUPPLY

12.5 ± 1 VOLTS

P44 J44

P20 J20

P1 J1

Speed/Timing Sensor Power Supply

The Speed/Timing Sensors have a dedicated power supply. The ECMsupplies 12.5 ± 1 Volts to the Primary and Secondary Speed/TimingSensors.

Connectors A and B send the common power supply to the sensors. TheC wires transmit separate signals to the ECM.

This power supply is not battery voltage, but is generated and regulatedwithin 1.0 volt by the ECM. A power supply failure at the ECM willcause both sensors to fail and the engine will shut down since the sensorsshare the common power supply.

NOTICE

Connecting another system or accessory to the Speed/Timing Sensorpower supply can cause engine failure.

STMG 672 - 109 -4/97

97


160532

A701-GYF726-YLA703-BRF726-YL

P2 J2

INJECTOR WIRING SCHEMATIC

SOLENOID 1 POWERSOLENOID 1/3 RETURNSOLENOID 3 POWER

ECM(3408/3412E)

401134

A702-PUF727-BUA704-GNF727-BU


321738

A705-BUF728-BRA707-PUF728-BR


282122

A706-GYF729-GNA708-BRF729-GN


372731

A709-ORF730-GYA711-PUF730-GY


183312

A710-GYF731-ORA712-BRF731-OR


1234

SOLENOID 1

SOLENOID 3

J52/P52

1234

SOLENOID 2

SOLENOID 4

J56/P56

1234

SOLENOID 5

SOLENOID 7

J53/P53

1234

SOLENOID 6

SOLENOID 8

J57/P57

1234

SOLENOID 9

SOLENOID 11

J54/P54

1234

SOLENOID 10

SOLENOID 12

J58/P58

Injector Power Supplies

The injectors are supplied with power from the ECM at 105 Volts. Forthis reason, precautions must be observed when performing maintenancearound the valve covers.

On the 3412E, two separate power supplies are used for the injectors. If afailure occurs, only one bank of injectors could have failed. (On the3408E, only one of the power supplies is used.)

If an open or a short occurs in the injector circuit, the ECM will disablethat injector. The ECM will periodically try to actuate that injector todetermine if the fault is still present and will disconnect or reconnect theinjector as appropriate.

STMG 672 - 110 -4/97

98

• Provides power to allanalog sensors


P22 J22

ENGINE COOLANTTEMPERATURE SENSOR

ENGINE OILPRESSURE SENSOR

+V ANALOGANALOG RETURNSIGNAL


P23 J23

TURBO OUTLETPRESSURE SENSOR


P25 J25



P27 J27

ATMOSPHERICPRESSURE SENSOR


P45 J45



3630

ANALOG SENSORPOWER SUPPLY

P1 J1

P43 J43



P51 J51


HYDRAULIC OILTEMPERATURE SENSOR

ABC

ABC

ABC

ABC

ABC

ABC

ABC

ABC

J21 P21

5 ± 0.2 VOLTS

ECM (3408E/3412E HEUI)+V ANALOG SUPPLYANALOG RETURN

Analog Sensor Power Supply

The Analog Sensor Power Supply provides power to all the analogsensors (pressure and temperature sensors).

The ECM supplies 5.0 ± 0.2 Volts DC (Analog Supply) through the J1/P1connector to each sensor.

A power supply failure will cause all analog sensors to appear to fail.

The power supply is protected against short circuits, which means that ashort in a sensor or a wiring harness will not cause damage to the ECM.

STMG 672 - 111 -4/97

99


ECM (3408E/3412E HEUI)+ V DIGITAL SUPPLY- V DIGITAL RETURN

2935

DIGITAL SENSORPOWER SUPPLY

P1 J1

ABC

J35 P35

ABC

P84 J84

+V DIGITALDIGITAL RETURN

SIGNAL

FAN SPEED SENSOR

THROTTLEPOSITION SENSOR


SIGNAL

8 ± 0.5 VOLTS

Digital Sensor Power Supply

The ECM supplies power at 8 ± 0.5 Volts through the J1/P1 connector tothe following circuits:

- Throttle Position Sensor- Fan Speed Sensor (if installed)- Exhaust Temperature Sensor (may be installed on high

performance industrial engines)

The power supply is protected against short circuits, which means that ashort in a sensor will not cause damage to the ECM.

STMG 672 - 112 -4/97

100

• 0 to 24 Volts digitalpower supply

• Injection actuationpressure test

ECM (3408E/3412E HEUI)+ SUPPLY- RETURN

2935

P2 J2

AB

J46 P46

PUMP CONTROLVALVE

SUPPLY RETURN

PUMP CONTROL VALVEPOWER SUPPLY

0 to 24 VOLTS PWM0 to 800 mAmps

Pump Control Valve Power Supply

The ECM supplies a PWM signal of 0 to 24 Volts (PWM) and 0 to 800 mA through the J2/P2 connector to the Pump Control Valve.

The control valve and power supply can be tested on the engine using ETand the Hydraulic Injection Actuation Pressure Test. Using the test, thepressure can be adjusted manually with the ET service tool fromminimum to maximum. Therefore, this function can be used to verify theoperation of the control valve, the power supply from the ECM and thehydraulic system.

When using the test, the pressure (expressed as a percentage of maximum)can be raised in increments of 1% up to 100%. The maximum value canonly be reached when there is a leak in the system and the pump is atmaximum displacement to make up for the pressure loss. Otherwise, thepressure may only reach a maximum of 49%. The minimum pressure is afunction of the spring setting of the Compensator Valve. (This valve is an emission control and should not be adjusted.) ➥

STMG 672 - 113 -4/97

• Indicated voltages

The service tool status screen can be used to show the percentage of thecurrent being used. This measurement can be used in conjunction withthe desired and actual hydraulic pressures to check the complete systemoperation.

The Pump Control Valve uses a digital power supply because a PWMcurrent is more easily regulated. Also, modulating the current at 500 Hzproduces a vibrating effect on the poppet valve to prevent the valve fromsticking. The poppet valve is kept in motion much like the rack in ahydra-mechanical governor.

NOTE: If the control valve voltage is read with an oscilloscope, itmay show a peak of 24 Volts, while a Voltmeter may show up to 8 Volts rms.

INSTRUCTOR NOTE: The following exercises will reinforce thematerial introduced in the preceding slides and will allow questions tobe answered.

During this exercise, a demonstration on an engine or a Training Aidshould be performed showing:

Open circuit in the ECM power supply

Status screen supply voltage reading

Opens and shorts in the Speed/Timing sensor power supply

Opens and shorts in the analog and digital power supplies

Status screen pressure and temperature readings with a fault inthe sensor power supply

Hydraulic Injection Actuation Pressure Test showing thepercentage of current to the control valve

STMG 672 - 114 -4/97

101

ELECTRONIC SENSORS AND SYSTEMS

ELECTRONIC SENSORS AND SYSTEMS

This section of the presentation covers the electronic sensors and relatedcircuits in the 3408E and 3412E HEUI fuel system.

STMG 672 - 115 -4/97

102

• Three functions of thespeed/timing sensor

• Self-adjusting zerogap sensor

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH



24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS

8 OR 12INJECTORS


DISCONNECT SWITCH


MACHINEHARNESS

Speed/Timing Sensors

Two Speed/Timing Sensors are installed: a primary and a secondary. TheSpeed/Timing Sensors serve three basic functions in the system:

- Engine speed detection

- Engine timing detection

- Cylinder and TDC identification

The Speed/Timing Sensors, which are mounted on the front housingbelow the timing gear wheel, are self-adjusting during installation.

This type of sensor does not have a typical fixed air gap. The sensor isnot in direct contact with the timing wheel but does run with a zeroclearance.

➥

STMG 672 - 116 -4/97

• Speed/timing sensorfailure modes

• Sensor installation

If a primary sensor failure occurs, the secondary sensor will provide theback-up automatically. A momentary change of engine sound is all thatwill be noticed as the changeover takes place.

If the fault in the primary sensor is corrected, then the ECM will continueto use the secondary sensor until the engine is shut down and restarted. Asubsequent speed/timing sensor failure will cause an engine shutdown.

The sensor may be functionally checked by cranking the engine andobserving the service tool status screen for engine rpm.

A failure of either sensor will be indicated by the active fault screen onthe service tool. An intermittent failure will be shown in the logged faultscreen.

Because both sensors share a common power supply, a power supplyfailure at the ECM will cause both sensors to fail.

The sensor head is extended prior to installation. The action of screwingin the sensor pushes the head back into the body after the head contactsthe timing wheel.

During installation, it is essential to check that the sensor head is notaligned with the wide slot in the timing wheel. If this condition occurs,the head will be severed when the engine is started, and some disassemblymay be necessary to remove the debris. Also, the other sensor may bedamaged by the debris.

STMG 672 - 117 -4/97

103

ANALOG SENSORS

• Fuel temperature

• Hydraulic temperature

• Lubrication oil pressure

• Turbocharger outlet pressure

• Turbocharger inlet pressure

• Atmospheric pressure

• Coolant temperature

• Hydraulic pressure

Analog Sensors and Circuits

The following analog sensors and circuits may be used in variousapplications:

- Hydraulic Pressure Sensor

- Coolant Temperature Sensor

- Atmospheric Pressure Sensor

- Turbocharger Inlet Pressure Sensor *

- Turbocharger Outlet (Boost) Sensor

- Lubrication Oil Pressure Sensor

- Hydraulic Oil Temperature Sensor

- Fuel Temperature Sensor

* Not all applications

STMG 672 - 118 -4/97

104

• Hydraulic pressuresensor

• Senses injectoractuation pressure

• System defaults

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY KEY

SWITCH




24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS

8 OR 12INJECTORS


DISCONNECT SWITCH


MACHINEHARNESS

The Hydraulic Pressure Sensor is located in the right side supply manifoldand is used to measure injector actuation hydraulic pressure for the ECM.

The ECM uses this pressure measurement to control the displacement ofthe Hydraulic Supply Pump (through the Pump Control Valve).

The sensor has a range from 0 to 4.8 Volts output which corresponds to apressure range of approximately 4000 to 33000 kPa (600 to 4800 psi).With the engine stopped, the default value when read with the service toolis 1800 kPa (260 psi).

The ECM will not activate the injectors to start the engine if the pressureis reading below 4500 kPa (650 psi). A fault will be generated if theactual hydraulic pressure differs from the desired system pressure by morethan 1000 kPa (145 psi) for more than half a second.

NOTE: Always use a wrench (not vise grip pliers) for removal andinstallation of all sensors.

STMG 672 - 119 -4/97

105

• Coolant temperaturesensor

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH




24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS


8 OR 12INJECTORS


DISCONNECT SWITCH


MACHINEHARNESS

The Coolant Temperature Sensor supplies the temperature signal for thefollowing functions:

- Caterpillar Monitoring System or VIMS instrument display- Caterpillar Monitoring System or VIMS warning lamps and alarm- Demand Control Fan (if so equipped)- ET or ECAP coolant temperature display- High coolant temperature event logged above 107°C (225°F) - Engine Warning Derate when 107°C (225°F) is exceeded or low

oil pressure occurs (if so equipped)- Back-up sensor to the hydraulic oil temperature sensor for ether

aid operation

NOTE: All analog sensors use the common analog power supply of5.0 ± 0.2 Volts.

STMG 672 - 120 -4/97

106

• Atmospheric pressuresensor

• Used to calculategauge pressure

• Two methods used tocalibrate sensors

• Four main functions

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH




24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS



8 OR 12INJECTORS


DISCONNECT SWITCH


MACHINEHARNESS

All pressure sensors (except hydraulic actuation) in the system measureabsolute pressure and, therefore, require the atmospheric sensor tocalculate gauge pressure. The sensors are used both individually (absolutepressure) in the case of atmospheric pressure, and as a pair to calculate oiland boost pressures (gauge pressures).

All the pressure sensor outputs are matched to the Atmospheric PressureSensor output during calibration. Calibration can be accomplished usingthe ET service tool or by turning on the key start switch without startingthe engine for five seconds to automatically calibrate the sensors. TheAtmospheric Pressure Sensor performs four main functions:

1. Automatic Altitude Compensation (maximum derate 24%)

2. Automatic Filter Compensation (maximum derate 20%)

3. Part of pressure calculation for gauge pressure readings

4. Reference sensor for pressure sensor calibration

A foam filter is installed below the sensor to prevent the entry of dirt.

STMG 672 - 121 -4/97

107

• Automatic altitudecompensation

• System continuallyadjusts to optimumpower setting

100%

98%

96%

94%

92%

90%

88%

86%

84%

82%

80%

78%

76%

74%

77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53

8,210

8,920

9,630

10,340

11,050

11,760

12,470

13,890

14,600

15,310

16,020

16,730

17,440

13,180

7,500

72%

ENGINE POWER DERATING MAPACCORDING TO ATMOSPHERIC PRESSURE

ATMOSPHERIC PRESSURE IN kPa

PE

RC

EN

T O

F F

UL

L L

OA

D P

OW

ER

AL

TIT

UD

E I

N F

EE

TAtmospheric pressure measurement by the sensor provides an altitudereference for the purpose of Automatic Altitude Compensation. The graph shown here describes how derating on a typical 3408E/3412Estarts at 7500 ft. and continues linearly to a maximum of 17000 ft. Otherengines may start as low as 4000 ft. depending on the application.

The advantage of the HEUI system is that the engine always operates atthe correct derating setting at all altitudes. The system continually adjuststo the optimum setting regardless of altitude, so the engine will not exhibita lack of power or have smoke problems during climbs or descents todifferent altitudes.

NOTE: The HEUI system has an advantage over a mechanical fuelsystem which is derated in "altitude blocks" (i.e. 7500 ft., 10000 ft.,12500 ft.). HEUI derating is continuous and automatic. Therefore, amachine operating in the lower half of the block is not penalized withlow power. Conversely, a machine operating in the upper half of theblock will not overfuel with the HEUI system.

STMG 672 - 122 -4/97

108

• Turbo inlet pressuresensor

• Sensors enableautomatic air filtercompensation

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH




24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS



8 OR 12INJECTORS



DISCONNECT SWITCH


MACHINEHARNESS

The Turbocharger Inlet Pressure Sensor is used with the AtmosphericPressure Sensor to measure air filter restriction.

These two sensors are used to enable the Automatic Air FilterCompensation function (if so equipped.)

This sensor is also used as a back-up to the Atmospheric Pressure Sensorfor Automatic Altitude Compensation.

STMG 672 - 123 -4/97

109

• Automatic filtercompensation

• Derating starts above30 in. ∆P

CAT

AUTOMATIC AIR FILTER COMPENSATION

TURBOCHARGERINLET PRESSURE

SENSOR

ATMOSPHERICPRESSURE

SENSOR

Filter differential pressure calculated with formula:Atmospheric sensor pressure - Turbo sensor pressure = ∆PFuel limited 2% per 4 inches H20 to max 20%

Automatic Filter Compensation means that the engine is protected againstthe effects of plugged filters. Derating is automatic as follows:

- Air filter restriction (∆P) exceeds 6.25 kPa (30 in. of water) *

- Engine power derating starts at the rate of 2% per 1 kPa of ∆P

- Maximum derate is 20%

- Event is logged when air filter restriction (∆P) exceeds 6.25 kPa(30 in. of water) *

* These specifications are typical examples. The actual values may varydepending on the application.

Derating is retained at the maximum ∆P until the key start switch iscycled off and on.

NOTE: If only one filter is plugged, the ET service tool andCaterpillar Monitoring System will display the highest ∆P of the two.Derating is also based on the highest ∆P of the two.

STMG 672 - 124 -4/97

110

• Turbo outlet pressuresensor

• Air/fuel ratio control

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH





24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS



8 OR 12INJECTORS



DISCONNECT SWITCH


MACHINEHARNESS

The Turbocharger Outlet Pressure Sensor measures absolute pressuredownstream of the aftercooler. Boost (gauge) pressure can be read withthe service tools. This measurement is a calculation using theAtmospheric Pressure and the Turbocharger Outlet Pressure Sensors.

A failure of this sensor can cause the engine to derate as much as 60%when the ECM defaults to a zero boost condition.

The function of the sensor is to enable the Air/Fuel Ratio Control whichreduces smoke, emissions and maintains engine response duringacceleration. The system utilizes boost pressure, atmospheric pressureand engine speed to control the air/fuel ratio. Engine fuel delivery islimited according to a map of gauge turbo outlet (boost) pressure andengine speed. The Air/Fuel Ratio Control setting is not adjustable inmachine applications.

INSTRUCTOR NOTE: The pressure calculations and purposes ofthese calculations for all sensors are tabulated later in thepresentation.

STMG 672 - 125 -4/97

111

• Oil pressure sensor

• Calculations are usedto determine gaugepressure

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH





24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS



OIL PRESSURE SENSOR

8 OR 12INJECTORS



DISCONNECT SWITCH


MACHINEHARNESS

Two pressure sensors are used for the measurement of oil (gauge)pressure:

- Oil Pressure Sensor

- Atmospheric Pressure Sensor

PRESSURE CALCULATIONS

MEASUREMENT MEASURED BY RESULT

Oil pressure [oil press (A) - atmospheric (A)] = oil pressure (GP)

These measurements are used to determine oil pressure for the ET servicetool, Caterpillar Monitoring System and to alert the operator that anabnormal condition exists. The sensor operating range is 0 to 690 kPa (0 to 100 psi) (A).

NOTE: (A) = absolute pressure

(GP) = gauge pressure ➥

STMG 672 - 126 -4/97

PRESSURE CALCULATIONS

MEASUREMENT MEASURED BY RESULT

1.Atmospheric pressure atmospheric sensor = ambient press (absolute)

2. Air filter differential Atmospheric - turbo inlet = filter ∆ pressure

3. Boost turbo outlet - atmospheric = boost (gauge press)

4. Manifold press. absolute turbo outlet sensor = boost (absolute press)

5. Oil pressure oil press - atmospheric = oil press (gauge press)

These measurements are used to determine:

1. Automatic Altitude Compensation

2. Automatic Air Filter Compensation (and Restriction Indication)

3. ET Boost Measurement

4. Caterpillar Monitoring System Oil Pressure Indication(Lubrication)

5. Altitude

NOTE: ∆ pressure = differential pressure

STMG 672 - 127 -4/97

112

• Oil pressure map

• Determines correctpressure for all rpm

OIL

PR

ES

SU

RE

IN

kP

a

600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 180060

80

100

120

140

160

180

200

220

240

260

280

300

ENGINE RPM

OIL PRESSURE MAP

1900

320

340

8.7

11.6

14.5

17.4

20.3

23.2

26.1

29

31.9

34.8

37.7

40.6

43.5

46.4

49.3

OIL

PR

ES

SU

RE

IN

PS

I

kPa x 0.145 = PSI

2000

Engine oil pressure varies with engine speed. As long as oil pressureincreases above the upper line after the engine has been started and isrunning at low idle, the ECM reads adequate oil pressure. No faults areindicated and no logged event is generated.

If the engine oil pressure decreases below the lower line, the followingoccurs:

- An event is generated and logged in the permanent ECM memory.

- A Category 3 Warning (alert indicator, action lamp and alarm) isgenerated on Caterpillar Monitoring System (if so equipped).

- The engine is derated (if so equipped) to alert the operator.

The two lines are sufficiently separated to prevent multiple alarms andevents or a flickering lamp. This pressure separation is referred to as"hysteresis."

STMG 672 - 128 -4/97

113

• Hydraulic oiltemperature sensor

• Enables automaticviscositycompensation

• Ether aid temperaturereference

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH

TURBO OUTLET (BOOST) PRESS. SENSOR




24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS



OIL PRESSURE SENSOR


8 OR 12INJECTORS



DISCONNECT SWITCH


MACHINEHARNESS

The Hydraulic (engine) Oil Temperature Sensor is used by the ECM tocompensate for the effects of oil temperature on fuel injector timing andfuel delivery. This compensation provides consistent engine operationthroughout a variety of operating conditions.

Cold start protection with Cold Mode Timing is activated when the oiltemperature decreases below a preset value of 60°C (140°F).

The ether injection system uses this sensor as its temperature reference.

NOTE: Without oil temperature monitoring, viscosity changes due tochanges in oil temperature could cause unacceptable variations inengine performance (including exhaust emissions).

STMG 672 - 129 -4/97

114

• Fuel temperaturesensor

• Enables fueltemperaturecompensation

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH


BACKUP CAMSPEED/TIMING SENSOR

PRIMARY CAMSPEED/TIMING SENSOR


24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS



OIL PRESSURE SENSOR

HYDRAULIC TEMP SENSOR


8 OR 12INJECTORS



DISCONNECT SWITCH


MACHINEHARNESS

The ECM uses fuel temperature measurement to make corrections to thefuel rate to maintain power regardless of fuel temperature (within certainparameters). This feature is called "Fuel Temperature Compensation."

The sensor output should be between 0.4 and 4.6 Volts.

STMG 672 - 130 -4/97

115

• Coolant flow switch

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH





24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS



OIL PRESSURE SENSOR



COOLANT FLOW SWITCH

8 OR 12INJECTORS



DISCONNECT SWITCH


MACHINEHARNESS

The Coolant Flow Switch is installed in the oil cooler inlet.

The switch connects the coolant flow terminal at the ECM P1/J1connector to the digital return (ground) at the same connector. Thisground is common with all digital sensors. The switch contacts arenormally open with no flow.

This circuit is used to provide the operator with a warning if a failure inthe coolant circuit causing no flow occurs.

The function may be checked using the status screen which will show ifflow is present. This function should be checked both with the enginerunning and stopped.

STMG 672 - 131 -4/97

116

• Throttle Position

• Pump Control Valve Signal

• Exhaust Temperature

DIGITAL SENSORS AND CIRCUITS

Digital Sensors and Circuits

The following digital sensors and circuits may be used in the HEUI fuelsystem:

- Throttle Position Sensor

- Pump Control Valve Signal

- Exhaust Temperature (not installed on machine engines at thistime)

STMG 672 - 132 -4/97

117

• Throttle positionsensor

• 8-Volt digital sensorpower supply

• Throttle functionalcheck

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY KEY

SWITCH





24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS



OIL PRESSURE SENSOR



COOLANT FLOW SWITCH

8 OR 12INJECTORS



THROTTLESENSOR

ACCELERATORPEDAL

DISCONNECT SWITCH


MACHINEHARNESS

The Throttle Position Sensor provides engine speed control for theoperator.

At engine start-up, the engine rpm is set to low idle for two seconds toallow an increase of oil pressure before the engine is accelerated.

The Throttle Position Sensor receives 8 Volts from the Digital SensorPower Supply at the ECM.

A functional check of the throttle control system can be performed byconnecting ET and monitoring the throttle position on the status screen asthe throttle is moved slowly in both directions. The status screen willshow between 0 and 100% of throttle position. (This reading should notbe confused with the duty cycle percentage.)

NOTE: This system eliminates all mechanical linkage between theoperator's engine speed controls and the governor (ECM).

STMG 672 - 133 -4/97

118

• Throttle positionsensor signal

• Control defaults to lowidle

90%

ON

OFF

ON

OFF

ON

OFF

10%

50%

DUTYCYCLE

DUTY CYCLE = PERCENT OF TIME ON VS PERCENT OF TIME OFF

1 CYCLE

= 90%

DUTYCYCLE

= 50%

DUTYCYCLE

= 10%

PULSE WIDTH MODULATED SIGNALS

A Pulse Width Modulated (PWM) signal output is sent from the ThrottlePosition Sensor to the ECM. A PWM signal eliminates the possibility ofan erroneous throttle signal due to a short causing a possible "run-away."

If a signal problem occurs, the control defaults to a desired engine speedof low idle. If the ECM detects an out-of-normal range signal, the ECMignores the Throttle Position Sensor signal and defaults to low idle.

The sensor output is a constant frequency Pulse Width Modulated (PWM)signal to the ECM. For example, the Off-highway Truck sensor producesa duty cycle of 10 to 22% at the low idle position and 44 to 52% at thehigh idle position. The duty cycle can be read by the ECAP Service Tooland some digital multimeters. The percent of duty cycle is translated intoa throttle position of 0 to 100% by the ECM, which can be read on the ETstatus screen.

Other applications differ in PWM values for low and high idle. Thesevalues can be seen in the Troubleshooting Guide for the appropriateapplication.

STMG 672 - 134 -4/97

119


ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY KEY

SWITCH





24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS

PUMP CONTROL VALVE



OIL PRESSURE SENSOR



COOLANT FLOW SWITCH

8 OR 12INJECTORS



THROTTLESENSOR

ACCELERATORPEDAL

DISCONNECT SWITCH


MACHINEHARNESS

The Pump Control Valve is used to control the swashplate angle in thehydraulic pump.

By varying the PWM signal from the ECM to the solenoid, the valvecontrols the volume of hydraulic flow to case drain (as previouslyexplained).

PWM signals for the Pump Control Valve are used to maintain precisecontrol of current values. The frequency of the power supply createsconstant valve movement which helps the valve to maintain stablepressures.

The Pump Control Valve may also be referred to as the "InjectionActuation Pressure Control Valve."

STMG 672 - 135 -4/97

120

• Ground levelshutdown switch

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH





24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS

PUMP CONTROL VALVE



OIL PRESSURE SENSOR



COOLANT FLOW SWITCH

8 OR 12INJECTORS




THROTTLESENSOR

ACCELERATORPEDAL

DISCONNECT SWITCH


MACHINEHARNESS

Engine Shutdown Systems

The Ground Level Shutdown Switch is connected to the ECM through themachine and engine wiring harnesses.

The switch signals the ECM to cut electrical power to the injectors, butmaintains power to the ECM.

This feature also enables the engine to be cranked without starting formaintenance purposes.

No other circuits may be connected to this system. The user definedshutdown may be used in conjunction with other circuits.

Not all machines will have this feature installed.

STMG 672 - 136 -4/97

121

• User definedshutdown input

• Safety feature

ECM (3408E/3412E HEUI)USER SHUTDOWN1

P2 J2

USER DEFINED SHUTDOWN

12

J3

USER SHUTDOWNDEVICE

The User Defined Shutdown feature (if installed) may be used to connectanother device to the system to shut down the engine (such as a customerinstalled fire suppression system). When the shutdown input is groundedfor one second, the engine will stop running. The input must be pulleddown below 0.5 Volts before the ECM will recognize the shutdown signal.

Operation of the User Defined Shutdown is logged as an event and can beshown on the ET status screen.

When installed on an Off-highway Truck, this feature is programmed tofunction only during the following conditions for safety reasons:

- Parking brake is ENGAGED

- Transmission is in NEUTRAL

- Machine ground speed is at zero

Not all machines will have this feature installed.

STMG 672 - 137 -4/97

122

• Two thermostatic fantypes:

- Variable speedclutch

- Hydraulic

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH





24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS

PUMP CONTROL VALVE



OIL PRESSURE SENSOR



COOLANT FLOW SWITCH

8 OR 12INJECTORS


FAN

FAN SPEED SENSOR

FAN CONTROL VALVE



THROTTLESENSOR

ACCELERATORPEDAL

DISCONNECT SWITCH


MACHINEHARNESS

Demand Fan Controls

Two types of thermostatic fans are used in 3408E/3412E machineapplications. Some Off-highway Trucks, Track-type Tractors, MotorGraders and Paving Products are equipped with a variable speed fan driveclutch. Some Wheel Loaders are equipped with a hydraulic fan drive.

Both systems use the ECM and the temperature sensor as the enginecoolant temperature reference and both are controlled by the ECM. If anelectrical failure of the systems occurs, the fans will go to maximum(100%) speed.

The advantages of the systems are:

1. Reduced fuel consumption in most conditions 2. Reduced engine overcooling at low ambient temperatures 3. Faster engine warm-up 4. More engine power available at the flywheel5. Reduced noise

STMG 672 - 138 -4/97

123

• Ether injectionparameters

28291940

ECM(3408E/E3412E)

ETHER SWITCH

308-YL

200-BK

P1 J1

ETHER INJECTION SYSTEM

ETHER SW LAMPDIGITAL RETURNETHER REQUESTETHER CONTROL

P2 J2

F708-YL998-BR721-GY710-BR

J3 P323 93921

RELAY

12

+24V

+310-PK

200-BKP37 J37

ETHERSTART VALVE TO ENGINE

FROMCYLINDER

Ether Injection System

The ECM controls the use of ether for cold starting. The ECM uses inputsfrom the speed/timing and hydraulic oil temperature sensors to determinethe need for ether. The coolant temperature sensor is used as a back-upfor the hydraulic oil temperature sensor.

The ECM cycles the ether for three seconds on and three seconds off.Actual flow is determined by engine speed and temperature. Etherinjection is disabled when the oil temperature exceeds 10°C (50°F) orengine speed exceeds 1200 rpm.

A manual mode allows ether injection when the above parameters permit.In the manual mode, a precise quantity of ether is injected. The etherinjection status can be read on the ET status screen.

STMG 672 - 139 -4/97

124

• CAT Data Link

• Link between varioussystems

• Service tool connector

VIMS DISPLAY MODULES

COMMUNICATION

ADAPTER

7X1701

CONTROL SERVICE TOOL

SERVICETOOL

CONNECTOR CAT DATA LINK

VIM

SM

AIN

MO

DU

LE

ADEM IIELECTRONIC

CONTROLMODULE

(ECM)

LAPTOPCOMPUTER

CATELECTRONIC TECHNICIAN

CAT Data Link

The CAT Data Link is the communication link between the ECM,EPTC II, Caterpillar Monitoring System, ET Service Tool, PC basedsoftware and other onboard/off board microprocessor based systems. TheCAT Data Link allows the various onboard systems to communicate witheach other through a two wire connection. Up to 10 systems can beconnected on a machine.

The CAT Data Link is used for programming and troubleshooting theelectronic modules used with Caterpillar service tools through the ServiceTool Connector. The ET service tool is connected through the ServiceTool Connector. If a Personality Module is not installed in the ECM, theservice tool will not be able to communicate with the ECM.

STMG 672 - 140 -4/97

125

• Data link wires twistedto reduce RFI

• Two data link systems

988F/990 CAT DATA LINK CIRCUIT

89

POWERTRAIN CONTROLMODULE

Cat Data Link +Cat Data Link -

2324

CMS

Cat Data Link +Cat Data Link -

DEHJ

76

3132

9371

893-GN892-BRE794-YLE-793-BU

J42 P3 J3 P1 J1 ECM

Cat Data Link +Cat Data Link -ATA Data Link +ATA Data Link -

SERVICE TOOLCONNECTOR

MACHINE INTERFACECONNECTOR

The CAT Data Link is a two wire (twisted pair) electrical connection usedfor communication between electronic modules that use the CAT DataLink. The cables are twisted to reduce radio frequency interference.

Typical systems connected by the data link are:

- ECM- Caterpillar Monitoring System Modules- Caterpillar ET or ECAP Service Tools - Transmission Control Module

The ECM communicates with the Caterpillar Monitoring System, VitalInformation Management System (VIMS) or Computer MonitoringSystem (CMS) to share engine information such as engine speed, engineoil pressure, coolant temperature, filter restriction, and electronic systemfaults.

Two Data link systems are used. The CAT Data Link circuit is used fornormal diagnostic and programming functions and the ATA Data Link isused for flash programming.

STMG 672 - 141 -4/97

• Logged events

• Event list

126

LOGGED EVENTS

• Engine overspeed

• Air inlet restriction

• User defined shutdown

• Hydraulic system pressure fault

• Abnormal hydraulic pressure

• Low (lube) oil pressure

• Loss of coolant flow

• High coolant temperature

• Low fuel pressure

Logged Events

Logged events as listed on the appropriate ET screen are conditions whichare abnormal to the operation of the engine (for example: hightemperature, low pressure or excessive engine speed). These conditionswould not normally be caused by an electronic problem.

Some of the parameters listed in this presentation are used in the ETevents list. They are:

- High coolant temperature above 107°C (225°F)

- Loss of coolant flow

- Low (lubrication) oil pressure (according to the oil pressure map)

- Abnormal injection actuation hydraulic pressure (low or high)

- Injection actuation pressure system fault

- User defined shutdown (if installed)

- Air inlet restriction (if installed)

- Engine overspeed histogram

- Low fuel pressure (industrial engine only)

➥

STMG 672 - 142 -4/97

• Passwords required toclear events

All the parameters listed on the previous page can be read on the ETstatus screens (except for a hydraulic system fault).

Events are not logged if an electronic fault is detected.

Passwords are required to clear events. This process would normally beperformed during an engine overhaul. At other times, the events wouldbe left as a record of the engine history prior to overhaul time.

STMG 672 - 143 -4/97

127

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH





24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS

PUMP CONTROL VALVE



OIL PRESSURE SENSOR

HYDRAULIC TEMP SENSOR


COOLANT FLOW SWITCH

8 OR 12INJECTORS


INSTRUMENTPANEL



SERVICE TOOL CONNECTOR

CAT DATA LINK

FAN

FAN SPEED SENSOR

FAN CONTROL VALVE



THROTTLESENSOR

ACCELERATORPEDAL

DISCONNECT SWITCH


MACHINEHARNESS

INSTRUCTOR NOTE: To reinforce this presentation, review thevarious sensor and component functions shown above.

The following tasks can be demonstrated:

Opens and shorts in analog and digital sensors

Status screens with pressure and temperature readings

Check switch status for all system switches

Opens and shorts in throttle sensor (check operation with ET)

Override fan speed control

Identify connectors, trace sensor circuits and perform continuitychecks

Check for active and logged faults

Check events and overspeed histogram

STMG 672 - 144 -4/97

128

MACHINE APPLICATIONS

MACHINE APPLICATIONS

This section of the presentation covers the specific systems and relatedcircuits in the 3408E/3412E HEUI fuel system in the followingapplications:

- D9R/D10R Track-type Tractors

- 988F/990 Series II Wheel Loaders

- 769D/771B/773B/775B Off-highway Trucks

- 3408E/3412E Industrial Engines

STMG 672 - 145 -4/97

129

• Throttle decelerationsensor

3529

ECM(3408E/3412E)

DECELERATIONPOSITION SENSOR

P1 J1

DECELERATION POSITION SENSOR CIRCUIT

+V DIGITAL SUPPLY

DIGITAL RETURN

P2 J2

24 DECEL POSITION

A700-OR998-BR

P38 J38

ABC


SIGNAL

F702-GN

D9R/D10R Track-type Tractors

The Throttle Deceleration Position Sensor works similarly to a throttleposition sensor, but in reverse. The Track-type Tractor has a deceleratorpedal which, when in the released position, is wide open (high idle) and,when fully depressed, is in the low idle position.

This digital sensor is identical to a normal throttle position sensor, but isconnected mechanically in reverse to function as described above. Thesensor position (% throttle) can be read on the service tool status screen.

The sensor functions in conjunction with the Throttle Switch.

STMG 672 - 146 -4/97

130

• Throttle switch

• Speed setting function

22081429

ECM(3408E/3412E)

THROTTLESWITCH

P1 J1

THROTTLE SWITCH CIRCUIT

THROTTLE - LOW IDLETHROTTLE - H.I. PARITYTHROTTLE - L.I. PARITYTHROTTLE - HIGH IDLEDIGITAL RETURN

F715-PUF718-BUF716-WHF717-YL998-BR

The Throttle Switch is used in conjunction with the throttle decelerationposition sensor to control engine speed. This momentary rocker switchreplaces the throttle lever in the previous mechanical fuel system.

When held in the forward position, the switch will cause the engine to goto high idle. If momentarily rocked to the rearward position, it will causethe engine to return to low idle.

If the switch is held in the forward position for two seconds with thedecelerator holding the rpm at the desired level, the engine speed will beset at that rpm. Subsequently moving the switch in either direction willmove the engine to low or high idle.

The switch position can be read on the service tool status screen.

STMG 672 - 147 -4/97

131

• Crank withoutinjection plug

252429

ECM(3408E/3412E)

CRANK WITHOUTINJECTION PLUG

P1 J1

CRANK WITHOUT INJECTION PLUG CIRCUIT

CRANK W/O INJECT (NO)720-GN719-BR

J24 P24

998-BR

321

CRANK W/O INJECT (NC)DIGITAL RETURN

BK

PLUG "HHH"

PLUG "JJJ"

BK

The Crank Without Injection Plug is used to disable the injectors formaintenance purposes. The plug "HHH" must be replaced by the plug"JJJ" to enable the Crank Without Injection feature.

One of the two plugs must be installed at all times or a diagnostic messagewill be generated.

The plugs are installed close to the ECM in the engine compartment.

STMG 672 - 148 -4/97

132

• Variable speed fandrive clutch

• Fan speed sensor

• Coolant temperaturesensor

• AC fan control

352913

ECM(3408E/E3412E)

ENGINE FANSPEED SENSOR

P1 J1

MECHANICAL ENGINE FAN CONTROL CIRCUIT

+V DIGITAL SUPPLYDIGITAL RETURN

P2 J2

197

25

VARIABLE FAN CLUTCHPWM DR AND SOL RETURNENGINE FAN SPEED

A700-OR998-BR

J84 P84

ABC


SIGNAL

F703-GY

P41 J41

BC

ENGINE FANSOLENOID VALVE

E799-BRF700-BU

A/C ON (INPUT FROMCOMPRESSOR SWITCH)

The cooling fans for some Off-highway Trucks, the D10R Track-typeTractor and the 24H Motor Grader are driven by a fan belt through avariable speed clutch which is controlled by the ECM. A solenoid valvevaries the oil pressure to the clutch to control the fan speed.

A digital speed sensor is used as a reference for fan speed and is mountedon the clutch. This sensor is powered from the digital power supply.

The Coolant Temperature Sensor is used as a reference for fan control asengine temperature varies. The speed of the fan is a function of coolanttemperature. Below 88°C (190°F), the fan rotates slowly. At 98°C(208°F), the fan speed is maximum. Between those temperatures, fanspeed is modulated. The fan speed control can be overridden by theservice tool for testing purposes. For safety reasons, the fan will rotateslowly when the engine is started cold.

The engine fan will turn at minimum speed when the air conditioningcompressor switch closes and sends a signal to the ECM.

STMG 672 - 149 -4/97

133

• Throttle lock enableswitch

• Throttle lock lamp

F706-PU

ECMP1 J1

13192927142024

Throttle Lock RH Brake (NO)Throttle Lock RH Brake (NC)Digital ReturnThrottle Lock ON LampThrottle Lock Set/DeclerateThrottle Lock Resume/AccelerateThrottle Lock ON/OFF

998-BR

RIGHT BRAKE PEDAL SWITCH

F721-GYF722-OR

THROTTLELOCK LAMP

J3 P3

2113-OR BATT+

F717-YLF718-BU

F719-BR

998-BR

998-BR

998-BR

998-BR

998-BR

THROTTLE LOCKSET/DECLERATION SW

THROTTLE LOCKRESUME/ACCLERATION SW

THROTTLE LOCK SW

THROTTLE LOCK CIRCUIT

988F/990 Series II Wheel Loaders

The Throttle Lock permits the operator to maintain engine speed withouthaving to hold the throttle down for long periods. A rocker switchenables the feature.

The Throttle Lock Lamp indicates the status of the Throttle Lock. Thelamp ON indicates the feature is active.

NOTE: The Throttle Lock System functions similarly to anautomotive speed control system, except that it controls engine speedwhile cruise control functions with ground speed.

➥

STMG 672 - 150 -4/97

• Set/decelerationswitch

• Resume/accelerationswitch

• Right brake pedalswitch

After the engine speed has been set by the throttle lock, the engine speedcan be reduced 20 rpm by momentarily pressing the Set/DecelerationSwitch. The engine speed can be lowered incrementally by 50 rpm persecond while holding the switch down.

The Resume/Acceleration Switch can be used to increase speed by 20 rpm by momentarily pressing the Resume/Acceleration Switch. Theengine speed can be raised incrementally by 50 rpm per second whileholding the switch down.

Depressing the Right Brake Pedal Switch will disable the throttle lock.An invalid brake switch signal will also disable the throttle lock feature.

STMG 672 - 151 -4/97

134

• Fan driven byhydraulic motor

• Hydraulic fan solenoidvalve

ECM(3408E/E3412E)P2 J2

1907

HYDRAULIC FANPWM DRIVE AND SOL RETURN

P86 J86

21

HYDRAULIC FANSOLENOID VALVE

E799-BR

F700-BU

HYDRAULIC ENGINE FAN CONTROL CIRCUIT

The 990 Series II Wheel Loader has an optional high ambient cooling fanwhich is driven by a hydraulic motor and controlled by the ECM.

The Hydraulic Fan Solenoid Valve controls the supply of oil to thehydraulic motor to increase or decrease fan speed.

The Coolant Temperature Sensor is used as a reference for fan control asengine temperature varies. Above 98°C (208°F), the fan speed ismaximum. As the temperature decreases below 95°C (203°F), the fanspeed is minimum.

Fan speed will also change as hydraulic pump output varies with enginespeed.

The fan speed control can be overridden by the service tool for testingpurposes. The fan speed will go to maximum if power to the controlvalve fails.

STMG 672 - 152 -4/97

135

• Caterpillar Monitoring System

R0

5

10

15

20

25

30

P

X100

24 VMPHkm/h

44

AUT

CATERPILLAR MONITORING SYSTEM

769C/771C/773B/775B Off-highway Trucks

The Caterpillar Monitoring System is an electronic monitoring systemused on some HEUI powered machines including Off-highway Trucks. Ithas a similar look to the VIMS and includes the following:

- Message Center Module

- Speedometer/Tachometer Module

- Four Gauge Cluster Module

- Action Lamp and Action Alarm

This system receives information over the CAT Data Link. The displaycomponents show the operator the condition of machine systems andsystem diagnostic information. This system replaces the ElectronicMonitoring System (EMS) on earlier trucks.

STMG 672 - 153 -4/97

• Caterpillar Pre-LubricationSystem

• Prelube components:

1. Prelube relay

2. Prelube motor

3. Prelube pump

136

An ECM controlled pre-lubrication system is installed on the 3400 HEUIengines in Off-highway Trucks.

The pre-lubrication pump and motor are activated by the key start switch.The system uses existing sensors to determine the need for pre-lubrication.

After oil pressure is determined, the Electronic ProgrammableTransmission Control (EPTC II) signals the starter motor to begincranking.

The purpose of the pre-lubrication system is to prime the lubricationsystem with oil prior to cranking the engine, fill the filters if they havebeen changed and, ultimately, to minimize wear on the engine bearingsduring cold starts.

This view shows the following components:

- Prelube relay (1)

- Prelube motor (2)

- Prelube pump (3)

➥

STMG 672 - 154 -4/97

This Caterpillar designed system should not be confused with other pre-lubrication systems. The Caterpillar Pre-Lubrication System is integratedinto the machine electronic system utilizing existing hardware.

To enable the Caterpillar Pre-Lubrication System, the system must beturned on using the electronic service tool. After the system has beenenabled, any time the operator turns the key start switch to the startposition, the sequence will be as follows:

1. The EPTC II will not normally engage the starter relays until theengine ECM senses 48 kPa (7 psi) from the oil pressure sensor.This information is transmitted over the CAT Data Link. If theCAT Data Link is inoperative, the EPTC II will signal the engineto start.

2. The engine will bypass the pre-lubrication cycle during any of thefollowing conditions:

- If the engine has been running within two minutes

- Coolant temperature is higher than 70°C (158°F)

- Engine oil temperature is higher than 54°C (129°F)

- Torque converter temperature is higher than 65°C (149°F)

3. If the engine or torque convertor is cold, the engine ECM will turnon the signal relay in the cab. This relay signals the pre-lubrication relay on the chassis to initiate the sequence.

4. The chassis mounted pump draws oil from the oil pan and directsit to the oil gallery. When 48 kPa (7 psi) oil pressure (using the oilpressure signal from the oil pressure sensor) is reached or 60 seconds has elapsed, the EPTC II will terminate pre-lubricationand engage the starter.

5. If the system "times out" after 60 seconds, a pre-lubricationsystem fault will be recorded in the ECM. After the system hastimed out, the engine should start regardless of oil pressure. Apre-lubrication fault should not cause a failure to start the engine.

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137

INLET AIR TEMP. SENSOR

SERVICE TOOL CONNECTOR

DATA LINK

EMSPANEL

DIAGNOSTIC LAMP

ALARM /WARNING LAMP

TO AIR SHUTOFF SOLENOID

TO ETHER SOLENOID RELAY

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH





24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS

PUMP CONTROL VALVE



OIL PRESSURE SENSOR



8 OR 12INJECTORS


PTO ENABLE/PTO UP/DOWN SWITCHESENGINE SHUTDOWN SWITCH

ETHER ENABLE/OVERRIDE SWITCHEMERGENCY STOP/VERIFY SWITCH

USER DEFINED SHUTDOWN

THROTTLE POSITION SENSOR

DISCONNECT SWITCH

INDUSTRIAL3408E/3412E HEUI SYSTEM

COMPONENT DIAGRAM

MACHINEHARNESS

FUEL PRESS. SENSOR

COOLANT LEVEL SWITCH

MAINTENANCE INDICATOR LAMP

3408E/3412E HEUI Industrial Engines

Although these industrial engines are very similar to the machine engines,some electronic differences exist between the machine and the industrialengines.

The industrial engine has some component and software differences.Some components have been deleted and replaced by others. Forexample, the coolant flow switch is deleted and a coolant level switchmay be installed as an option.

A sophisticated Engine Warning System can be programmed to providedifferent levels of warning, derating and shutdown. These customerprogrammable parameters can be tailored to the customer's requirements.A complete description of these parameters is provided in the appropriateTroubleshooting Guide.

➥

STMG 672 - 156 -4/97

The component differences are:

Switches

PTO Enable and Up/Down Switch

Idle/Rated Speed Switch

Emergency Stop Verify Switch (for Air Shutoff Solenoid)

Engine Shutdown Switch

Sensors and Switches

Inlet Air Temperature Sensor (optional)

Coolant Level Sensor (optional, replaces the Coolant Flow Switch)

Fuel Pressure Sensor (optional)

Miscellaneous Components

Air Shutoff Solenoid

Alarm and Diagnostic and Maintenance Indicator Lamps

Caterpillar Engine Monitoring System

Software features

Engine Warning Derate and Shutdown for:

High coolant temperature

Low oil pressure

Low coolant level

PTO operation

Programmable Low Idle, Top Engine Limit and High Idle

Maintenance Indicator

Programmable Ether Aid

Engine Speed and Load Histogram

Multiple Engine Ratings with a Personality Module

Ramp Speed (engine acceleration rate in PTO mode)

Power Trim

STMG 672 - 157 -4/97

138

PUMPCONTROL

VALVE

OILFILTER

OILCOOLER

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR

HYDRAULIC OILTEMPERATURE

SENSORCOLD START


SENSOR

ECM

HYDRAULICSUPPLY

PUMPGROUP

COOL DOWNCIRCUIT

FUEL TANK

FUELTEMPERATURE

SENSOR

PRESSUREREGULATING

VALVE

SECONDARYFUEL

FILTER

FUELTRANSFER

PUMP

PRIMARYFUEL FILTER

WATERSEPARATOR

LUBE OILPUMP

TO LUBESYSTEM

FLUID MANIFOLD

FLUID MANIFOLD


CONCLUSION

The 3400 HEUI Engine control is a sophisticated system. However, likemany modern electronic controls, it is user friendly and simpler to servicethan previous pump and line systems. The key to this simplicity isexcellence in training.

INSTRUCTOR NOTE: The circuits described in this presentation onthe various HEUI applications can be demonstrated with the servicetool. The following tasks can be performed:

Opens and shorts in circuits

Status screens to show speed control sensor and switch positions

Override fan controls

Pre-lubrication functional test

Program industrial engine parameters

1. Title slide2. 3408 engine overview3. HEUI fuel system4. HEUI system major components5. 3408E engine top view6. 3408E engine upper left side view7. Timing calibration connector and hydraulic

pressure sensor8. Coolant temperature sensor9. Secondary speed/timing sensor

10. Timing wheel11. Turbo inlet sensor12. Turbo outlet sensor13. Identify components14. Lubrication oil pressure sensor15. Lubrication oil pump16. Timing calibration sensor17. Water separator18. Engine component identification19. Electronic control system20. ECM21. Personality module22. Injector23. Injector testing methods24. Timing control logic25. Electronic governor26. Component diagram27. Speed/timing sensors28. Timing wheel29. Speed/timing wheel30. Cranking31. After pattern recognition32. Normal operation33. Timing calibration sensor34. Timing calibration35. Injection current waveform36. Poppet valve movement37. Waveform and response characteristics38. Fuel system limits39. Fuel system cold modes40. Fuel system derates41. Fuel injection system42. HEUI fuel system43. System components44. Hydraulic supply pump group

45. HEUI fuel system--low pressure46. HEUI fuel system--high pressure47. HEUI fuel system--low pressure48. Injector--fuel and oil flow49. Injector fuel supply50. Fluid supply manifold (iron shot)51. Fluid supply manifold (sectional view)52. Jumper tube53. Injector current waveform54. Waveform and response55. Injector components56. HEUI unit injector--three main groups57. HEUI injector component parts58. Unit injector components59. Unit injector installation60. Valve body group61. Barrel group--fuel pressure62. Nozzle group63. Valve body group--solenoid de-energized64. Unit injector--end of injection65. Barrel group--refill66. Nozzle group--fuel edge filter67. Injection rate shaping graph68. Barrel prime rate shaping69. Barrel group--internal leaks70. Injector check valves71. Hydraulic injection pressure control72. Hydraulic supply pump group73. Hydraulic supply pump mounting adapter74. Hydraulic supply pump priming75. Fuel transfer pump76. Pressure regulating valve77. Cool down bypass circuit78. Reverse flow check valves (iron shot)79. Reverse flow check valve (sectional view)80. Hydraulic supply pump (cutaway front view)81. Hydraulic supply pump (cutaway side view)82. Fuel system--hydraulic system operation83. HEUI hydraulic control system--start-up84. Compensator assembly--start-up85. HEUI hydraulic control system--destroke86. Compensator valve--destroke87. HEUI hydraulic control system--upstroke88. Compensator valve--upstroke89. HEUI hydraulic control system--limiter

SLIDE LIST

STMG 672 - 158 -4/97

90. Compensator assembly--pressure limiteroperation

91. Pump control valve--no current flow92. Pump control valve--high current flow93. HEUI system power supplies94. Components diagram--power supply95. ECM power supply circuit96. Speed/timing sensor power supply97. Injector wiring schematic98. Analog sensor power supply99. Digital sensor power supply

100. Pump control valve--power supply101. Electronic sensors and systems102. Speed/timing sensor103. Analog sensor list104. Hydraulic pressure sensor105. Coolant temperature sensor106. Atmospheric pressure sensor107. Engine power derating map108. Turbocharger inlet pressure sensor109. Automatic filter compensation110. Turbocharger outlet sensor111. Oil pressure sensor112. Oil pressure map113. Hydraulic temperature sensor

114. Fuel temperature sensor115. Coolant flow switch116. Digital sensor list117. Throttle position sensor118. Pulse Width Modulated (PWM) signal119. Pump control valve120. Ground level shutdown switch121. User defined shutdown input122. Demand fan controls123. Ether injection system124. Cat Data Link diagram125. Cat Data Link circuit126. Logged events127. System diagram 128. Machine applications129. Deceleration position sensor circuit130. Throttle switch circuit131. Crank without injection plug circuit132. Engine fan control circuit133. Throttle lock circuit134. Hydraulic engine fan control135. 769C - 775B Dash136. Pre-lubrication system137. Industrial engine component diagram138. HEUI fuel diagram

SLIDE LIST

STMG 672 - 159 -4/97

STMG 672 - 160 - Serviceman's Handout No. 14/97

MODOS EN FRIO HEUI

MODO EN_FRIO PROPOSITO PUNTOS DE_CAMBIO SENSORDE TEMPERATURA

Control de VelocidadBaja en vacio_elevado Calentamiento rapido < 60°C Temp. aceite

Engine protection

Limitacion de CombustibleCranking limit Improves starting by limiting fuel < 60°C Temp. aceite

Prevents overfuelling during start-up

Fuel Temperature Provides advertised power between 30°C to 90°C Fuel temp.Compensation these between these values regardless

of fuel temperature changes

Sincronizacion de InyeccionOil Viscosity Compensates for variations due to < 60°C Oil temp.Compensation viscosity changes with oil temperature

Cold Mode Timing Optimum timing for cold running < 60°C Oil temp.also reduces white smoke

Presion de InyeccionCold mode cranking Optimum hydraulic pressure for < 60°C Oil/Coolanthydraulic pressure cold starting temp.

Cold mode running Optimum hydraulic pressure for < 60°C Oil temp.hydraulic pressure cold running

Oil Viscosity Compensates for variations due to All temperatures Oil temp.Compensation viscosity changes with oil temperature

Ether InjectionEther injection Starting aid < 10°C Oil temp.

HEUI - Material_de_EstudianteRef : 1672-01

5 Micron.0002 Inch.005 mm


2.5 Micron.0001 Inch.0025 mm


Human Hair88 Micron.0035 Inch.0889 mm

Magnified 2,000 times

How small is a Micron?

25,400 Microns = 1 Inch


SESV1672-01 Printed in U.S.A.

4/97

curso heui.pdf

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