3412 generator set 4bz00001-up(sebp2785 - 48) - documentation

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Welcome: apache0Product: GENERATOR SETModel: 3412C GENERATOR SET 4BZConfiguration: 3412 Generator Set 4BZ00001-UP

Systems Operation3412 Generator Set EnginesMedia Number -RENR1388-06 Publication Date -01/08/2015 Date Updated -26/08/201

i0249253

Electronic Control System Components

SMCS -1900


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Illustration 1 g01246160

Right side view

(1) Electronic Control Module (ECM)

(2) Coolant level sensor connector

(3) Rack position sensor

(4) Boost pressure sensor connector

(5) Engine coolant temperature sensor

(6) Engine oil pressure sensor

(7) Speed sensor

(8) Atmospheric pressure sensor


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View A-A

(9) Fuel shutoff solenoid

(10) Rack solenoid (BTM)

(11) ATA data link

The electronic control system is designed into the engine's fuel system. The system is designed to electronicallycontrol the delivery of fuel and injection timing.

The engine uses the following three types of electronic components:

Input component

Control component

Output component

An input component is one that sends an electrical signal to the ECM of the system. The signal that is sent variein either of the following ways:

Voltage

Frequency

The ECM interprets the signal from the input component as information about the condition, environment, oroperation of the engine.


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A control component (ECM) receives the input signals from the input components. Electronic circuits inside thecontrol component evaluate the signals from the input components. These electronic circuits also supplyelectrical energy to the output components of the system. The electrical energy that is supplied to the outputcomponents is based on predetermined combinations of input signal values.

An output component is one that is operated by a control module. The output component receives electricalenergy from the control group. The output component uses that electrical energy in one of two ways. The outputcomponent can use that electrical energy in order to perform work. As an example, a moving solenoid plungerwill perform work. The output component can use that electrical energy in order to provide information. As an

example, a dash panel light or an alarm will provide information to the operator of the engine.

These electronic components provide the ability to electronically control the engine operation. Engines withelectronic controls offer the following advantages:

Improvement in performance

Improvement in fuel consumption

Reduction in emissions levels

Various sensors feed engine data to the ECM. These sensors modify the following functions:

Boost pressure

Engine oil pressure

Engine speed

Fuel rack position

Throttle position

On/off ignition

The ECM processes the data. Then, the ECM sends electronic signals to the fuel injection solenoids. The fuelinjection solenoids move the fuel rack. This will optimize the efficiency and the performance of the engine.

The electronic engine control system also has the following built-in functions:

Engine overspeed

On board diagnostics

Data Link

A data link is used for the following items:

Communicate engine information.

Communicate with Caterpillar Electronic Technician Cat ET.

Calibrate the electronic engine control system.

Troubleshoot the electronic engine control system.


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Program the electronic engine control system.

The electronic engine control system includes a Data Link. The Data Link communicates with othermicroprocessor based devices. These devices are compatible with SAE Recommended Practices J1708 andJ1587. The Data Link can reduce the duplication of sensors by allowing the controls to share information.

The Data Link is used to communicate engine information to other electronic control systems. Also, the DataLink can interface with Cat ET.

The Data Link monitors engine information. The engine information that is available on the Data Link includesthe following information:

Boost pressure

Engine identification

Engine speed

Oil pressure

Rack position

Status and diagnostic information

Throttle position

The Cat ET is used to program the customer specified parameters.

The Cat ET is one method of programming the customer specified parameters that are selected by the customer.The tool plugs into the Data Link Connector. This allows the tool to communicate with the ECM. Also, the CatET can be used to display the real time values of all the information available on the Data Link. This will helpdiagnose engine problems.

System Diagnostic Codes

Table 1

Diagnostic Flash Codes

Flash Code Description of Code

21 Sensor Supply Voltage Fault

22 Rack Position Sensor Fault

24 Oil Pressure Sensor Fault

25 Boost Pressure Sensor Fault

26 Atmospheric Pressure Sensor Fault

27 Coolant Temperature Sensor Fault

32 Throttle Position Sensor Fault

33 Engine RPM Signal Fault


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34 Loss Of Engine Speed Signal

35 Engine Overspeed Warning

42 Check Boost Sensor Calibration

43 Rack Subsystem Fault

45 Shutoff Solenoid Fault

46 Low Engine Oil Pressure Warning

48 Excessive Engine Power

51 Intermittent Battery Power to ECM

52 ECM or Personality Module Fault

53 ECM Fault

55 No Detected Faults

56 Check Customer or System Parameters

61 High Coolant Temperature Warning

62 Low Coolant Temperature Warning

Refer to Electronic Troubleshooting Guide for a complete explanation of the Diagnostic Codes.

Electronic Control Module (ECM) and Personality Module


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ECM and personality module

(1) Electronic Control Module (ECM)

(2) Fuel outlet

(3) Fuel inlet

(4) Personality module

The 3412C generator set engine uses an ECM microprocessor. The ECM is mounted on the top of theaftercooler housing. The ECM (1) and the personality module (4) are cooled by fuel. The fuel circulates througha manifold between two circuit boards in the control module. The fuel enters the control module from the fueltransfer pump. The fuel enters the control module through the fuel inlet (3). Then, the fuel exits the controlmodule through the fuel outlet (2) .

The inputs and the outputs to the control module are designed to withstand the short circuits to the batteryvoltage without damage to the control. The electronic engine control system has the following features that aredesigned into the system.

Resistance to radio frequency

Resistance to electromagnetic interference

The system has passed tests for interference that is caused by two-way radios and by switching noise.

The ECM power supply provides electrical power to all engine mounted sensors and actuators. The followingprecautions have been designed into the ECM.


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Reverse voltage polarity protection

Vessel power system voltage swings or surges due to sudden alternator load

In addition to acting as a power supply, the ECM also monitors all sensor inputs. The ECM provides the correctoutputs. Also, the ECM ensures the desired engine operation.

The ECM memory stores and identifies a selected factory engine rating. The memory also contains a personalitymodule identification code. This code is used to avoid unauthorized tampering or switching of personality

modules and other pertinent manufacturing information.

The wiring harness provides communications to the following areas:

Various sensors

Data link connector

Engine connectors

The personality module is attached to the ECM. The personality module provides all the instructions necessaryfor the ECM to function. The personality module contains the engine performance information and the

certification information. This certification information includes fuel ratio information and rack control maps fora particular ratings group that utilizes common engine components.

The ECM is programmed to perform the following functions:

Diagnostic tests on all inputs

Diagnostic tests on all outputs

Will separate a fault to a specific circuit

Once a fault is detected, the fault can be displayed on a diagnostic lamp. The diagnostic code can be read by

using Cat ET. A multimeter can be used to check most problems. Also, a multimeter can be used to troubleshootmost problems. The ECM will either log or record most diagnostic codes that are generated during engineoperation. These logged or intermittent codes can be read by Cat ET.

Throttle Control Sensor

A throttle control sensor is used to interface with the throttle. The throttle control sensor output is a constantfrequency, pulse width modulation (PWM) signal rather than an analog voltage. Refer to pulse width modulationin the glossary. The PWM signal overcomes the serious errors that can result from analog signals. These errorsoccur from the following problems.

Leakage between pins

Contamination in the wiring harness

Contamination in the connectors

The engine returns to low idle if the PWM signal is invalid due to a broken or shorted wire.

Fuel Rack Controls


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Cross section view of the rack housing

(1) Shutoff solenoid

(2) Rack solenoid (BTM)

(3) Fuel rack servo


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Cross section view of rack position sensor

(4) Fuel rack

(5) Rack position sensor

(6) Shutoff override shaft and lever assembly (manual shutoff)


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Cross section view of engine speed sensor

(7) Flywheel starter gear

(8) Engine speed sensor

Engine oil pressure is used to move the fuel rack. An electronically actuated rack solenoid (BTM) (2) controls adouble acting hydraulic servo. The servo directs engine oil pressure to either side of a piston that is connected tothe fuel rack. The oil pressure moves the piston. The piston moves the fuel rack.

The servo group is a gerotor type oil pump. The servo group increases the pressure of the engine oil that issupplied to the governor. The increased oil pressure allows a better regulation of engine speed during the rapidapplication or the removal of heavy loads on the engine.

The rack solenoid (BTM) (2) is installed in the side of the rack actuator housing on the fuel injection pump. Therack solenoid (BTM) (2) is controlled by the ECM. The lever of the rack solenoid (BTM) is engaged in a collar

on the rack servo valve. The rack solenoid (BTM) is spring loaded toward the fuel off position and must receivea positive voltage in order to move in the fuel on position.

Rack position sensor (5) is located inside the rack actuator housing. The rack position sensor is attached to thefuel rack by a magnet. The rack position sensor is a linear potentiometer that provides accurate feedbackinformation for the ECM.

In addition to the rack position data, the ECM receives data from other sensors that are located in the rackactuator housing. The engine speed sensor (8) is triggered by radial slots on the flywheel. Oil pressure, inlet air

pressure, and the boost pressure sensors are mounted on the engine. These sensors are connected to the ECM.The ECM will limit engine speed and power output of the engine if low oil pressure occurs. When there is a


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change in boost and/or inlet air pressure, the control module adjusts the quantity of fuel or the timing of fuel thatis delivered to the engine.

The ECM operates an energized to run type shutoff solenoid (1). If the rack solenoid (BTM) (2) is unable tomove the fuel rack to the fuel off position, the shutoff solenoid will apply an addition force on the fuel rack tomove the rack to the fuel off position. A manual shutoff (6) (shutoff override shaft and lever assembly) is

provided. The manual shutoff control shaft is spring loaded to a neutral position.

If the shutoff solenoid fails to energize, the solenoid override may be used to move the shutoff lever away from

the fuel rack servo (3). This will allow the rack solenoid (BTM) to move the fuel rack even though the shutoffsolenoid is not energized.

The manual shutoff may be used to shut down the engine with the shutoff solenoid energized and powermaintained to the ECM. This method of shut down is used in some troubleshooting procedures.

The mechanical fuel ratio control, torque control group, and various adjustment screws have been eliminated.The electronic control module performs all of these functions. The control module adjusts the engine power andthe torque rise. This compensates for the operation of the engine that either has plugged air cleaners or to limitthe amount of smoke.

The amount of fuel that is needed by the engine to maintain a desired rpm is determined by the ECM. With theengine running at a desired speed, the engine speed will decrease when an additional load is applied. The signalfrom the engine speed sensor (8) to the ECM changes. The control module performs the following tasks:

Receives the signal and other data

Processes all the data

Sends a positive voltage to the rack solenoid (BTM)

The rack solenoid (BTM) moves the valve in fuel rack servo (3). This will cause the fuel rack to move in theFuel On direction. The increase in fuel to the engine will increase engine speed. This action will continue until

the engine is again running at the desired speed or until the rack position has increased up to a rack positionlimit.

With the engine running at a desired speed, the engine speed will increase when the load is decreased. The ECMreceives the changed signal from the engine speed sensor (8). The ECM reduces the electrical signal that goes tothe rack solenoid (BTM). The rack solenoid (BTM) moves the valve in the fuel rack servo (3). This will movethe fuel rack in the Fuel Off direction. The decrease in fuel to the engine will decrease engine speed. This actionwill continue until the engine is again running at the desired speed.

The electronic engine control system allows the engine to be cranked and then allows the engine to start. Thethrottle control is not needed. The ECM will automatically provide the engine with the correct amount of fuelthat is required to start the engine. Since some oil pressure is required for the fuel rack servo to move the fuel

rack, electronically controlled engines may require a slightly longer cranking time to start.

Governor Servo


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Rack movement toward Full Fuel

(1) Piston

(2) Cylinder

(3) Sleeve

(4) Valve

(5) Fuel rack

(A) Oil inlet

(B) Oil outlet

(C) Oil passage

(D) Oil passage

When the rack solenoid (BTM) is energized, the rack solenoid (BTM) moves valve (4) to the left. The valveopens oil outlet (B) and the valve closes oil passage (D). Pressure oil from oil inlet (A) pushes piston (1) andfuel rack (5) to the left. Oil behind the piston goes through oil passage (C), along valve (4) and exits through oiloutlet (B).


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No rack movement (const ant engine speed )

(1) Piston. (2) Cylinder. (3) Sleeve. (4) Valve. (5) Fuel rack. (A) Oil inlet. (B) Oil outlet. (C) Oil passage. (D) Oil passage.

(1) Piston

(2) Cylinder

(3) Sleeve

(4) Valve

(5) Fuel rack

(A) Oil inlet

(B) Oil outlet

(C) Oil passage

(D) Oil passage

When the desired engine speed is reached, the rack solenoid (BTM) holds valve (4) in a fixed position. Piston(1) moves to the left until both oil outlet (B) and oil passage (D) are blocked by valve (4). Oil is trapped in thechamber behind piston (1). This creates a hydraulic lock. The piston and the fuel rack movement is stopped.


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Rack movement toward fuel off

(1) Piston

(2) Cylinder

(3) Sleeve

(4) Valve

(5) Fuel rack

(A) Oil inlet

(B) Oil outlet

(C) Oil passage

(D) Oil passage

When the rack solenoid (BTM) is de-energized, spring force in the solenoid moves valve (4) to the right. Thevalve closes oil outlet (B) and opens oil passage (D). Pressure oil from oil inlet (A) is now on both sides of

piston (1). The area of the piston is greater on the left side than the area of the piston on the right side. The forceof the oil is also greater on the left side of the piston. The piston and the fuel rack (5) moves to the right.

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3412 generator set 4bz00001-up(sebp2785 - 48) - documentation

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