msts ignition system

MICROPROCESSORSPARK TIMING SYSTEM

(MSTS)LATE MODEL

GM 3.0L AND 4.3L LPG FUEL ENGINES

PART NO. 1473385 2200 SRM 765

SAFETY PRECAUTIONSMAINTENANCE AND REPAIR

When lifting parts or assemblies, make sure all slings, chains, or cables are correctlyfastened, and that the load being lifted is balanced. Make sure the crane, cables, andchains have the capacity to support the weight of the load.

Do not lift heavy parts by hand, use a lifting mechanism.

Wear safety glasses.

DISCONNECT THE BATTERY CONNECTOR before doing any maintenance or repairon electric lift trucks.

Disconnect the battery ground cable on internal combustion lift trucks.

Always use correct blocks to prevent the unit from rolling or falling. See HOW TO PUTTHE LIFT TRUCK ON BLOCKS in the Operating Manual or the Periodic Mainte-nance section.

Keep the unit clean and the working area clean and orderly.

Use the correct tools for the job.

Keep the tools clean and in good condition.

Always use HYSTER APPROVED parts when making repairs. Replacement partsmust meet or exceed the specifications of the original equipment manufacturer.

Make sure all nuts, bolts, snap rings, and other fastening devices are removed beforeusing force to remove parts.

Always fasten a DONOTOPERATE tag to the controls of the unit whenmaking repairs,or if the unit needs repairs.

Be sure to follow theWARNING and CAUTION notes in the instructions.

Gasoline, Liquid PetroleumGas (LPG), Compressed Natural Gas (CNG), and Diesel fuelare flammable. Be sure to follow the necessary safety precautions when handling thesefuels and when working on these fuel systems.

Batteries generate flammable gas when they are being charged. Keep fire and sparksaway from the area. Make sure the area is well ventilated.

NOTE: The following symbols and words indicate safety information in thismanual:

WARNINGIndicates a condition that can cause immediate death or injury!

CAUTIONIndicates a condition that can cause property damage!

Microprocessor Spark Timing System (MSTS) Table of Contents

TABLE OF CONTENTS

General ............................................................................................................................................................... 1Description ......................................................................................................................................................... 2What MSTS Does........................................................................................................................................... 2How MSTS Begins Operation ....................................................................................................................... 2

Operation............................................................................................................................................................ 3Distributor ..................................................................................................................................................... 3Ignition Coil ................................................................................................................................................... 3Ignition Module.............................................................................................................................................. 3When Engine Is Being Started ..................................................................................................................... 4When Engine Is Running .............................................................................................................................. 5Manifold Absolute Pressure (MAP) Sensor.................................................................................................. 6Engine Coolant Temperature (ECT) Sensor................................................................................................. 6MSTS Module Corrections ............................................................................................................................ 7

Troubleshooting.................................................................................................................................................. 8General........................................................................................................................................................... 8Tools and Test Equipment ............................................................................................................................. 10MSTS.............................................................................................................................................................. 11Troubleshooting Procedure............................................................................................................................ 11Where to Start ........................................................................................................................................... 11Visual/Physical Inspection ........................................................................................................................ 11Knowledge/Tools Required........................................................................................................................ 11Damage from Static Discharge (Static Electricity) ................................................................................. 11

Troubleshooting Information ........................................................................................................................ 12Malfunction Indicator Lamp (MIL) .......................................................................................................... 12Connecting CodeMate Tester.................................................................................................................... 12Reading Diagnostic Trouble Codes (DTC)................................................................................................ 13Clearing Diagnostic Trouble Codes (DTCs)............................................................................................. 14

On-Board Diagnostic (OBD) System Check ................................................................................................. 14Test Description......................................................................................................................................... 14

No Malfunction Indicator Lamp........................................................................................................................ 16Circuit Description ........................................................................................................................................ 16Test Description ............................................................................................................................................. 16

No DTC-12, Malfunction Indicator Lamp ON.................................................................................................. 18Circuit Description ........................................................................................................................................ 18Test Description ............................................................................................................................................. 18

Starter Rotates Engine, Engine Does Not Run................................................................................................ 19Test Description ............................................................................................................................................. 19

DTC-14 Engine Coolant Temperature (ECT) (Low Temperature Indicated).................................................. 23Circuit Description ........................................................................................................................................ 23Test Description ............................................................................................................................................. 23

DTC-15 Engine Coolant Temperature Sensor (ECT) (High Temperature Indicated) .................................... 25Circuit Description ........................................................................................................................................ 25Test Description ............................................................................................................................................. 25

DTC-34 Manifold Absolute Pressure (MAP) Sensor ........................................................................................ 27Circuit Description ........................................................................................................................................ 27Test Description ............................................................................................................................................. 27

DTC-41 Electronic Spark Timing (EST) Open Circuit..................................................................................... 30Circuit Description ........................................................................................................................................ 30Test Description ............................................................................................................................................. 30

DTC-42 Electronic Spark Timing (EST) Grounded Circuit ............................................................................. 32Circuit Description ........................................................................................................................................ 32

2002 HYSTER COMPANY i

Table of Contents Microprocessor Spark Timing System (MSTS)

TABLE OF CONTENTS (Continued)

Test Description ............................................................................................................................................. 32DTC-51 MSTS Failure ....................................................................................................................................... 34Circuit Description ........................................................................................................................................ 34

Distributor Repair.............................................................................................................................................. 34Remove ........................................................................................................................................................... 34Disassemble ................................................................................................................................................... 35Inspect ............................................................................................................................................................ 35Assemble ........................................................................................................................................................ 35Install ............................................................................................................................................................. 36Ignition Timing .............................................................................................................................................. 36

Ignition Module Repair...................................................................................................................................... 37Test For Fault ................................................................................................................................................ 37Replace ........................................................................................................................................................... 38

Sensing Coil Repair ........................................................................................................................................... 38Test For Fault ................................................................................................................................................ 38Replace ........................................................................................................................................................... 38

Ignition Coil Repair ........................................................................................................................................... 39Test For Fault ................................................................................................................................................ 39Remove ........................................................................................................................................................... 39Install ............................................................................................................................................................. 39

MSTS Module Repair......................................................................................................................................... 40Remove ........................................................................................................................................................... 40Install ............................................................................................................................................................. 40

ECT Sensor Replacement .................................................................................................................................. 40MAP Sensor Replacement ................................................................................................................................. 41

This section is for the following models:

GM 3.0L and 4.3L LPG Fuel Engines

ii

2200 SRM 765 General

GeneralThis section describes the operation of the Micropro-cessor Spark Timing System (MSTS). The MSTS ig-nition system is used on engines that use an LPG fuelsystem. The description, operation, troubleshooting,and repair of the MSTS is identical for both the GM

3.0L and 4.3L engines. Illustrations in this man-ual show the MSTS in the 3.0L engine only. Repairsand Troubleshooting procedures are also in this sec-tion. Typical installation of the MSTS is shown inFigure 1.

1. ENGINE COOLANT TEMPERATURE (ECT)SENSOR

2. DISTRIBUTOR3. MSTS MODULE

4. TACHOMETER CONNECTOR5. IGNITION COIL6. MAP SENSOR

Figure 1. MSTS Arrangement in Engine Compartment (Typical)

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Description 2200 SRM 765

DescriptionThe general operation of the MSTS system is de-scribed in the following paragraphs. The descriptionof the components and a circuit analysis is given inthe paragraphs under Operation.

WHAT MSTS DOESThe MSTS module receives signals from sensorsmounted on the engine and electronically processesthe information to adjust the ignition timing for thebest fuel use and engine performance. See Figure 2.

Figure 2. MSTS Module

The MSTS module receives signals from the follow-ing sensors:

Manifold Absolute Pressure (MAP) sensor. Thissensor is a pressure transducer that measures theatmospheric pressure before the engine is started.The MSTS module uses this pressure as a refer-ence. This sensor then measures changes in pres-sure in the intake manifold during engine opera-tion.

Engine Coolant Temperature sensor (ECT). Thissensor is a thermistor (resistor that is calibratedto change its value as its temperature changes).

The ignition module is a small electronic modulewithin the distributor. This module is a signal con-verter that senses the operation of the distributor.A sensing coil in the distributor senses the rotationof the timer core and the ignition module sensesthe speed of rotation. A square wave generator inthe ignition module converts the pulses from thesensing coil to a square wave signal that is sentto the MSTS module. If the signals from the igni-tion module to the MSTS indicate that the engineis rotating at less than 400 rpm, the MSTS moduledetermines that the engine is being rotated by thestarter. The ignition module controls the ignitionfor an engine being started. The Electronic SparkTiming (EST) function from the MSTS module isdeenergized. If the signals from the ignition mod-ule to the MSTS module indicate that the engine isrotating at greater than 400 rpm, the MSTS mod-ule determines that the engine is running and theElectronic Spark Timing (EST) controls the igni-tion.

Figure 3. Electronic Engine Control System

HOW MSTS BEGINS OPERATIONWhen the ignition switch is turned to ON, the MSTSmodule measures the atmospheric pressure (BARO

signal) from the MAP sensor. See Figure 3. TheMSTS module also checks the signal from the en-gine coolant temperature sensor (ECT). When the

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2200 SRM 765 Operation

starter is engaged, the ignition module sends elec-tronic pulses to the MSTS module. The frequency ofthe pulses indicates to the MSTSmodule that the en-gine is being started. The ignition module also elec-tronically energizes (ON) and deenergizes (OFF) theprimary circuit of the ignition coil to create a sparkat the spark plugs.

When the engine starts, the frequency of the pulsesfrom the ignition module increases and indicates tothe MSTS module that the engine is running. The

MSTS module then sends a bypass signal to the ig-nition module that removes control of the spark (ig-nition) timing from the ignition module. The MSTSmodule takes control of the ignition timing and fol-lows its program to give ignition timing for the bestengine operation. When the engine is operating, theMSTS module continuously checks the signals fromthe MAP, ECT, and distributor speed to make timingadjustments for the engine operating conditions.

OperationDISTRIBUTORThe distributor uses an internal magnetic pickup as-sembly that consists of a permanent magnet, polepiece with internal teeth and pickup coil. See Fig-ure 4. When the rotating teeth of the timer core (per-manent magnet) line up with the teeth of the polepiece, voltage is induced in the pickup coil. Thisvoltage signals the ignition control module to triggerthe primary ignition circuit bypass mode. Currentflow in the primary circuit is interrupted and a highvoltage of up to 35,000 volts is induced in the igni-tion coil secondary winding. This high voltage is di-rected through the secondary ignition circuit to firethe spark plugs.

The principle of magnetic induction also controls thepolarity of the voltage generated in the pickup coil.An increasing magnetic field will generate a voltagein the coil that is the opposite polarity of a magneticfield that is decreasing. This signal pulse causes theintegrated circuits in the ignition module to gener-ate a square wave signal. The ignition module and amagnetic pulse generator control the primary circuitto the ignition coil when the engine is started. Afterthe engine is started, the MSTS module receives thesquare wave signal from the magnetic pulse genera-tor and ignition module as one of the signals to con-trol the EST. The pole piece has the same number ofteeth as the engine has cylinders so that a spark volt-age is correctly sent to each spark plug as the shaftin the distributor rotates.

IGNITION COILThe ignition coil generates a secondary voltage of upto 35,000 volts. The ignition coil connects to the dis-tributor cap through a high voltage wire. There aretwo connectors on the coil used for battery voltage in-put, primary voltage output to the ignition module,

trigger signal from the ignition module and the tachoutput signal.

1. ROTOR2. TIMER

CORE/SHAFT3. RETAINER4. SHIELD

5. COIL6. POLE PIECE7. IGNITION MODULE8. HOUSING

Figure 4. Distributor

IGNITION MODULEThe ignition module is a solid-state electronic devicethat operates like a fast switch except that it does nothave any moving or mechanical parts. See Figure 5.Small electrical pulses from the sensing coil of thepulse generator go to the ignition module.

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Operation 2200 SRM 765

The MSTS module must always know the speed atwhich the engine is operating. The engine speed sig-nal is generated by the ignition module. The signalconverter in the ignition module changes the signalvoltage from the sensing coil to a square wave refer-ence signal to the MSTS module. This square wavereference signal for engine speed is called REF HI.TheMSTSmodulemust also have a reference to com-pare with REF HI. An additional wire between theMSTS module and the ignition module is called REFLO. The REF HI and REF LO connections give theEEPROM in the MSTS module the necessary infor-mation about engine speed.

The other two wires between the MSTS module andthe distributor control the Electronic Spark Timingand are called EST and BYPASS.

NOTE: The ignition module controls spark timingonly when the engine is being started. The MSTSmodule controls the spark timing during engine oper-ation. The ignition module will also control the sparktiming if there are some failures in the signals to theMSTS module. This backup mode of operation willoften permit operation of the engine so that the lift

truck can be moved to an area for repair. The re-sults of the failures in signals to the MSTS moduleis described in the paragraphs under MSTS ModuleCorrections.

WHEN ENGINE IS BEING STARTEDWhen the engine is rotated by the starter, the elec-tronic relay is in the deenergized position. SeeFigure 5. The sensing coil is connected through thesquare wave generator to the base of the transistor.

When the sensing coil applies a positive voltage (thesquare wave voltage is increasing) to the transistor,the transistor goes ON. When the voltage from thesensing coil changes to negative (the square wavevoltage is decreasing), the transistor goes OFF.When the transistor is ON, current flows throughthe primary winding of the ignition coil. When thetransistor goes OFF, the current flow through theprimary winding stops. The changing magnetic fieldin the primary winding generates a high voltage inthe secondary winding of the ignition coil. This highvoltage generates a spark at the spark plug.

Figure 5. Ignition Module When Engine is Being Started

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Legend for Figure 5

NOTE: THE NUMBER IN FRONT OF THE PIN DENOTES THE CONNECTOR. FOR EXAMPLE, 6E IS PIN E ONTHE 6-PIN CONNECTOR WHILE 5E IS PIN E ON THE 5-PIN CONNECTOR.

1. IGNITION MODULE2. ELECTRONIC RELAY3. SQUARE WAVE GENERATOR4. SENSING COIL

5. MSTS MODULE6. BATTERY VOLTAGE7. TO IGNITION COIL8. TRANSISTOR

WHEN ENGINE IS RUNNINGWhen the engine speed is approximately 400 rpm,the MSTS module determines that the engine is run-ning and applies 5 volts on the BYPASS wire to theignition module. See Figure 6. This voltage ener-gizes the electronic relay and makes the following

changes: The EST wire is not grounded and is nowconnected to the base of the transistor. The sensingcoil is disconnected from the base of the transistor.

The ignition module and the ignition timing is nowcontrolled by the EST signal from the MSTS module.This mode of operation is called the EST mode.

NOTE: THE NUMBER IN FRONT OF THE PIN DENOTES THE CONNECTOR. FOR EXAMPLE, 6E IS PIN E ONTHE 6-PIN CONNECTOR WHILE 5E IS PIN E ON THE 5-PIN CONNECTOR.

1. IGNITION MODULE2. ELECTRONIC RELAY3. SQUARE WAVE GENERATOR4. SENSING COIL

5. MSTS MODULE6. BATTERY VOLTAGE7. TO IGNITION COIL8. TRANSISTOR

Figure 6. Ignition Module When Engine is Running

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Operation 2200 SRM 765

MANIFOLD ABSOLUTE PRESSURE (MAP)SENSORThe Manifold Absolute Pressure (MAP) sensor isa pressure transducer that measures changes inthe pressure in the intake manifold. See Figure 7.The pressure changes are a result of engine loadand speed changes. The MAP sensor converts thesepressure changes to a signal voltage to the MSTSmodule.

1. SENSOR2. ELECTRICAL CONNECTOR

Figure 7. MAP Sensor

The MSTS module sends a 5-volt reference signalto the MAP sensor. When the pressure in the in-take manifold changes, the electrical resistance intheMAP sensor also changes. The change in the volt-age signal from the MAP sensor enables the MSTSmodule to sense the pressure in the intake manifold.

A closed throttle causes a low pressure (high enginevacuum) in the intake manifold. This low pressurecauses a low voltage signal from the MAP sensor tothe MSTS module. A fully opened throttle causes ahigher pressure (low engine vacuum) in the intakemanifold. This higher pressure causes a higher volt-age signal from theMAP sensor to theMSTSmodule.These pressure changes indicate the load on the en-gine to the MSTS module. The MSTS module thencalculates the spark timing for the best engine per-formance.

The MAP sensor also measures the barometric pres-sure when the key switch is turned to ON and before

the engine is started. The MSTS module remembersthe barometric pressure (BARO signal) after the en-gine is running. The MSTS module then automat-ically adjusts the ignition timing for different alti-tudes and atmospheric conditions.

ENGINE COOLANT TEMPERATURE (ECT)SENSORThe engine coolant temperature (ECT) sensor (Fig-ure 8) is a resistor that changes its resistance valuewhen the temperature changes (thermistor). Thissensor is installed in the engine coolant system. Alow coolant temperature makes the thermistor havea high resistance [100,700 ohms at 40 C ( 40 F)].A higher coolant temperature makes the thermistorhave a lower resistance [70 ohms at 130 C (266 F)].

1. TEMPERATURE SENSOR2. ELECTRICAL CONNECTOR3. LOCK TAB

Figure 8. Engine Coolant Temperature (ECT)Sensor

The engine coolant temperature sensor uses a ther-mistor to control the signal voltage (see Figure 9)to the MSTS module. The MSTS module applies a5-volt reference voltage to the ECT. The referencevoltage will be high when the engine coolant is cold.The reference voltage will be lower when the enginecoolant is at operating temperature. TheMSTSmod-ule will adjust the ignition timing for more spark ad-vance when the engine coolant is cold and less sparkadvance when the engine coolant is hot.

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1. MSTS MODULE2. MSTS IGNITION FUSE3. IGNITION COIL4. SPARK PLUGS5. TACHOMETER CONNECTOR

6. DISTRIBUTOR AND IGNITION MODULE7. MAP SENSOR8. ENGINE COOLANT TEMPERATURE SENSOR9. DIAGNOSTIC CONNECTOR10. MSTS B+ FUSE

Figure 9. MSTS Wiring Diagram

MSTS MODULE CORRECTIONSThe operation of the MSTS module was describedin earlier paragraphs. (See the description in WhatMSTS Does.) These paragraphs describe the correc-tions made by the MSTS module.

The MSTS module does a check of the system com-ponents. A set of normal operating limits are partof the PROM program. If a sensor sends a signalthat is outside of the limits of the PROM program,the MSTS module will not use the information. The

MSTS module will use a standard value from its pro-gram and continue to operate the MSTS.

The following examples are the action of the MSTSmodule if it finds a problem:MAP Sensor Signal Voltage Is Too High OrToo Low. TheMSTSmodule will use aMAP valuefrom its PROM program and use this value to cal-culate the ignition timingECT Signal Voltage Is Too High Or Too Low.When a coolant sensor error occurs, the MSTSmodule will use a value that is approximately thenormal operating temperature of the coolant.

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Troubleshooting 2200 SRM 765

Open Circuit In The EST Circuit From TheMSTS Module To The Ignition Module. If theEST circuit is open, it cannot be at ground poten-tial, and the EST signal will rise and fall from thesensing coil. If the EST circuit becomes open whenthe engine is running, the engine stops but willrestart and run in the backup mode from the igni-tion module.Short Circuit (Grounded Circuit) In The ESTCircuit From The MSTS Module To The Igni-tion Module. When the engine is being rotatedby the starter, the MSTS module normally detects0 volts in the EST circuit because the circuit is atground potential in the ignition module.

The MSTS module would not detect a problem un-til the engine began to run. The MSTS modulecould not operate in the EST mode and the enginestops when the module switches to EST mode. Ifthe EST circuit has a short-circuit (grounded cir-cuit) when the engine is running, it will stop.

Open Circuit Or Short Circuit In The BY-PASS Circuit. The MSTS module would not de-tect a problem until the engine began to run. TheMSTS module could not operate in the EST modeand the engine would operate in the bypass modefrom the ignition module. If this problem occurswhen the engine is running, the engine continuesto run but switches to the backup mode from theignition module.Open Circuit Or Short Circuit In The REFHI Circuit. The MSTS module would not detectthat the engine was operating. The MSTS modulecould not operate in the EST mode and the enginewould operate with reduced economy. If this prob-lem occurs when the engine is running, the enginecontinues to run but switches to the backup modefrom the ignition module.Open Circuit In The REF-LO Circuit. Thiscircuit provides a ground for the ignition moduleand the MSTS. If this circuit were open, it maycause poor performance.

TroubleshootingGENERAL

WARNINGThis troubleshooting requires the operation ofthe engine for some of the tests. Make sure thetests are done carefully to prevent injury: Put the lift truck on a level surface. Lowerthe carriage and forks and apply the park-ing brake. Make sure the lift truck cannotmove and cause an injury during the tests.Put blocks in front and back of the drive tiresto prevent movement of the lift truck.

The fuel system and the engine must operatecorrectly. Any problems or leaks in the fuelsystem or the engine must be repaired beforedoing troubleshooting on the MSTS.

The fan and the drive belts can remove fin-gers or cause other injuries. Be careful thatyour hands and tools do not touch the mov-ing fan or the drive belts.

The engine exhaust and other parts of the en-gine are hot. Do not touch a hot surface andcause a burn.

CAUTIONElectronic equipment can be damaged if trou-bleshooting and repairs are not done correctly.The following CAUTIONS must be followed

when doing troubleshooting or repairs on anengine with MSTS: Always disconnect the battery negative cablebefore disconnecting and removing any partsof ignition system.

Never disconnect the battery from any equip-ment when the engine is running.

If the battery must be charged with a bat-tery charger, ALWAYS disconnect the batteryfrom the electrical system.

Make sure that all electrical connections areclean and have good electrical contact.

Never connect or disconnect the wiring har-ness at theMSTSmodulewhen the key switchis ON.

Always disconnect the battery and the MSTSmodule connectors if electric arc weldingmust be done on the vehicle.

Make sure that any water or steam is notsent toward the MSTS module or its sensorsif the engine compartment is cleaned withsteam. The heat and steam can damage theelectronic components and cause corrosionin the electrical connections.

Use only the tools and test equipment de-scribed in Tools and Test Equipment toprevent damage to good components and toobtain correct test results.

8

2200 SRM 765 Troubleshooting

All voltage measurements must be done witha digital voltmeter with a minimum rating of10 megohm input impedance.

When a test light is used in troubleshooting,the test light must have less than 0.3 amps(300 milliamps) of maximum current flow. A

test for a correct test light is shown in Fig-ure 10.

The following troubleshooting diagrams are designedto give an efficient method of fault analysis on theMSTS. The MSTS connector pin assignments andfunctions are shown in Table 1.

Table 1. MSTS Module Connections

This voltage chart is for use with a digital voltmeter when doing troubleshooting. There can be smallvariations in the voltage shown in the chart from those voltages measured during troubleshooting. Thesesmall variations are because of the battery charge and other resistances in the connections. A variation ofmore than 0.5 volts can be an indication of a malfunction.When this chart is used for troubleshooting, the engine must be at its operating temperature and the enginemust be at idle speed (for ENGINE RUNNING column).

MSTS 6-Pin Connector Sensor Connector Normal Voltage

Pin Function Pin Function Key ON EngineRunning

A Distributor Reference C Ignition Control Module 5.0 5.0

B Ignition Control D Ignition Control Module - -

C Bypass B Ignition Control Module 0 5.0

D ECT Sensor B MSTS to ECT Sensor 0 1.5 - 2.02

E MAP Sensor Signal B Manifold Absolute Pressure 4.751 1.01

F +5 Volt Reference C Manifold Absolute Pressure 5.0 5.0

MSTS 5-Pin Connector Connector Normal Voltage


A Ignition Feed Alternator EXC Terminal andCoil

12 12

B Battery Feed A B+ (Fuse Connector) B+ B+

C Alternate Fuel Not Used 0 0

D Knock Signal Not Used 0 0

E MSTS Ground Engine Ground 0 0

MSTS 3-Pin Connector Diagnostic Connector Normal Voltage3


A Data G - -

B Malfunction Indicator Lamp(MIL)

E Malfunction Indicator Lamp - -

C Diagnostic Test Terminal B - -1 Voltage changes with atmospheric pressure.2 Voltage changes with temperature.3 Not applicable.

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TOOLS AND TEST EQUIPMENTThe following tools are necessary for troubleshootingthe MSTS: Digital-Volt-Ohmmeter (DVOM). The voltmetermust have a minimum input impedance of10-megohms. (A digital voltmeter and ohm-meter are normally included in a multimeter testinstrument.)

Tachometer with inductive trigger signal sensor. Test light that has a low current draw as describedin Figure 10.

Vacuum pump with a gauge. This vacuum pump isheld and operated with the hand. The gauge mustbe able to indicate a gauge pressure (vacuum) of34 kPa (10 inHg)]. See Table 2.

Spark tester. The spark tester (ST125) is used tocheck the secondary ignition.

Diagnostic Trouble Code tester. Rinda Tech-nologies CodeMate Tester (Hyster part number3071579) or equivalent.

Table 2. Pressure Conversion Chart

Absolute Pressure GaugePressure

kPa Inches ofHg

Inches ofHg

121.57 36 6

114.81 34 4

108.06 32 2

101.31 30 0

94.55 28 2

87.80 26 4

81.04 24 6

74.29 22 8

67.54 20 10

60.78 18 12

54.03 16 14

47.28 14 16

40.52 12 18

33.77 10 20

27.01 8 22

20.26 6 24

Vacuum and pressure readings often cause confusionbecause everyone does not use the same point of reference.Absolute pressure is gauge pressure plus the atmosphericpressure. Standard atmospheric pressure is also called thestandard barometric pressure and is equal to 101.325 kPa(14.695 psi) or [29.92 inches of mercury (Hg)] at sea level.The reference point for these measurements is zero pressureor an absolute vacuum. The conversion formula used inconverting inches of mercury to kPa is:Inches of Hg 3.37685 = kPa

Service people normally use gauge pressure as the referencepoint which does not add the atmospheric pressure. Thereference point for gauge pressure is atmospheric pressure.It is important to know when reading a pressure chartwhether the units are given in absolute pressure or gaugepressure.

The gauges used by most service people indicate gaugepressure. However, most gauges calibrated in a metric scale(kilopascals) and used to measure less than atmosphericpressure normally indicate absolute pressure as shown inthe chart. A gauge calibrated in inches of Hg and usedto measure a vacuum begins at zero and increases itsindication as the vacuum increases as shown in the gaugepressure column of the chart.

An additional cause of confusion is that the manifoldpressure gauge for an engine with a turbochargeris normally calibrated for absolute pressure for bothkilopascals and inches of Hg. The MAP sensor described inthis section is also calibrated for absolute pressure, but theservice person doing checking or troubleshooting will oftenbe using gauges calibrated for gauge pressure.

13.51 4 26

Pressure

- - - - -

Vacuum

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CAUTIONIf the ammeter indicates less than 0.3 amps(300 milliamps), the test light can be used.

If the ammeter indicates more than 0.3 amps(300 milliamps), the test light cannot be usedbecause it can cause damage to the electroniccomponents.

1. DC AMPS2. TEST LIGHT

3. BATTERY

Figure 10. Current Flow Test for Test Light

MSTSThe MSTS has the ability to perform some trou-bleshooting of itself and of other parts of the system.When a problem is found, the MSTS turns the mal-function indicator lamp in the CodeMate Tester toON. A diagnostic trouble code (DTC) is kept in thememory of the MSTS.

TROUBLESHOOTING PROCEDUREBefore using this part of the manual, you need toknow the information and the correct troubleshoot-ing procedures. If the correct troubleshooting proce-dures are not followed, as described in this section, itcan result in replacement of good parts.

Where to StartThere are three things to do to start troubleshooting.The first item is to become familiar with the elec-tronic engine control system.

Secondly, always start your work with a good visual/physical inspection. See the following paragraph formore explanation.

The last item on the Where-To-Start list is theOn-Board Diagnostic (OBD) System Check.

Visual/Physical InspectionA careful visual and physical inspection must bedone as part of any diagnostic procedure. Thiscan cause the repair of a problem without furthersteps. Inspect all vacuum hoses for correct routing,restrictions, cuts or faulty connections. Be sure toinspect hoses that are difficult to see beneath the airfilter. Inspect all wires in the engine compartmentfor proper connections, damaged spots, or contactwith sharp edges or the exhaust manifolds. Thisvisual/physical inspection is very important. It mustbe done carefully.

Knowledge/Tools RequiredTo use this manual most effectively, a general un-derstanding of basic electrical circuits and circuittesting tools is required. One should be familiarwith wiring diagrams, the meaning of voltage, ohms,amps, the basic theories of electricity, and under-stand what happens in an open or shorted wire. Toperform the troubleshooting procedures, the use of adiagnostic CodeMate Tester is required. A tachome-ter, test lamp, ohmmeter, digital voltmeter with 10megohms impedance, vacuum gauge, and jumperwires are also required. Special tools that are re-quired for system service and the ones describedabove are shown at the end of this section.

Damage from Static Discharge (StaticElectricity)

CAUTIONTo prevent damage to the MSTS by static elec-tricity, do not touch MSTS connector pins.

Electronic components used in control systems use avery low voltage and can be easily damaged by staticdischarge or static electricity. Less than 100 volts

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of static electricity can cause damage to some elec-tronic components. There are several ways for a per-son to become statically charged. The most commonmethods of charging are by friction and by induction.An example of charging by friction is a person slid-ing across a car seat; in which a charge of as muchas 2 to 5,000 volts can build up. Charging by induc-tion occurs when a person with well insulated shoesstands near a highly charged object and momentar-ily touches ground. Charges of the same polarityare drained off, leaving the person highly chargedwith the opposite polarity. Static charges of eithertype can cause damage; therefore, it is important touse care when handling and testing electronic com-ponents.

TROUBLESHOOTING INFORMATIONThe troubleshooting diagrams and function checksin this section are designed to find a faulty circuitor component through logic based on the process ofelimination. The diagrams are prepared with therequirement that the vehicle functioned correctly atthe time of assembly and that there are no multiplefailures. The MSTS does constant testing on certaincontrol functions. The MSTS communicates thesource of a malfunction with Diagnostic TroubleCodes (DTC). The DTCs are two digit numbers thatcan range from 12 to 99. When a malfunction isfound by the MSTS, a DTC is set and the CodeMateTester malfunction indicator lamp is turned ON.DTC codes for this MSTS are shown in Table 3.

Table 3. MSTS Diagnostic Codes

Code Description IndicatorLamp ON

12 Indicates that the fault monitor system is operating. No

14 Engine Coolant Temperature Sensor Circuit - Low Temp Indicated Yes

15 Engine Coolant Temperature Sensor Circuit - High Temp Indicated Yes

34 MAP Sensor Circuit Yes

41 Ignition Control (IC) System. Open EST Circuit Yes

42 Ignition Control (IC) System. Grounded EST Circuit, Open orGrounded Bypass Circuit.

Yes

51 Checksum Error Yes

Malfunction Indicator Lamp (MIL)The malfunction indicator lamp on the CodeMateTester has three functions:1. To test that the lamp is functioning2. To indicate a malfunction has occurred3. To display the diagnostic trouble codes (DTC)

kept by the MSTS which help the techniciantroubleshoot system problems.

Follow the steps described in Connecting CodeMateTester to install it onto the engines Diagnostic LinkConnector.

Connecting CodeMate Tester1. Turn the engine ignition switch to OFF.

2. Locate the engine diagnostic connector.

3. Place the CodeMate Tester test switch to OFFand plug the CodeMate into the diagnostic con-nector.

NOTE:Make sure to slide the CodeMate Tester com-pletely into the diagnostic connector so that the con-nectors locking tab clicks into place.

As a bulb and system check, the lamp comesONwiththe ignition switch ON and the engine not running.When the engine is started, the lamp turns OFF.

If the lamp remainsON, the system has found a prob-lem. This problem is referred to as a current DTC. Ifthe problem goes away, the lamp goes out after tenseconds. In either condition a DTC remains in theMSTS.

When the lamp remains ON while the engine is run-ning, or when there is a malfunction, the On-BoardDiagnostic (OBD) System Check must be done.

12


When a problem is not regular or constant, the mal-function indicator lamp will turn ON for approxi-mately ten seconds and then will turn OFF. How-ever, the diagnostic trouble code (DTC) will be kept inthe memory of the MSTS until the DTCs are cleared(see DTC clearing in this section). A DTC that isnot constant can reset. If it is a problem that is notconstant, a DTC diagram is not used. When trou-bleshooting is complete, turn the ignition switch toOFF, and disconnect the CodeMate Tester.

Reading Diagnostic Trouble Codes (DTC)

CAUTIONTo prevent MSTS damage, the key must beOFF when disconnecting or reconnectingMSTS power.

The diagnostic connector is used to communicatewith the MSTS. See Figure 11. The diagnostic con-nector is installed on the bracket near the MSTS. Itis used in the assembly plant to receive informationin checking that the engine is operating correctlybefore it leaves the plant. The DTC(s) kept in theMSTSs memory can be read with a CodeMate Testerconnected to the diagnostic connector.

1. DIAGNOSTIC CONNECTOR

Figure 11. Diagnostic Connector

Use the following steps to read trouble codes.

1. Install the CodeMate Tester into the diagnosticconnector. See the preceding section, ConnectingCodeMate Tester.

2. Turn the ignition key to ON but do not start theengine.

3. Place the CodeMate Tester test switch to ON.This puts the MSTS in the diagnostic mode.

4. Observe the sequence of flashes on the CodeMatemalfunction indicator.

At this point, the malfunction indicator lamp onthe CodeMate Tester flashes DTC 12 three timesconsecutively (see Figure 12). The following isthe flash sequence for DTC 12: long pause, flash,pause, flash-flash, long pause, flash, pause,flash-flash, long pause, flash, pause, flash-flash.DTC 12 (which means no crankshaft rpm signal)indicates that the MSTSs diagnostic system isoperating correctly at this time. If DTC 12 is notindicated, a problem is in the diagnostic systemitself.

Following the output of DTC 12, if additionalcodes are stored, the malfunction indicator lampflashes the DTC three times. If more than oneDTC is stored in the MSTSs memory, the DTCsare flashed starting with the lowest DTC setand finishing with the highest DTC set. Whenall DTCs have been flashed, the sequence startsover again with DTC 12.

5. When testing is complete, place the CodeMatetest switch toOFF, turn the ignition key toOFF,and disconnect the CodeMate Tester from the di-agnostic connector.

6. Secure the diagnostic connector to the MSTSbracket.

13


1. LONG PAUSE 2. FLASH 3. PAUSE 4. FLASH-FLASH

Figure 12. Diagnostic Trouble Code-12 Example

Clearing Diagnostic Trouble Codes(DTCs)To clear the stored Diagnostic Trouble Codes from theMSTS, do the following.

1. Install the CodeMate Tester into the diagnosticconnector. See the preceding section ConnectingCodeMate Tester.

2. Turn the ignition key to ON, but do not start theengine.

3. Place the CodeMate test switch to the ON posi-tion.

4. Turn the ignition switch to OFF for five seconds.

5. Turn the ignition switch to ON and verify thatDTC-12 is the only code in the MSTS memory.

6. When testing is complete, place the CodeMatetest switch toOFF, turn the ignition key toOFF,and disconnect the CodeMate Tester from the di-agnostic connector.

7. Secure the diagnostic connector to the MSTSbracket.

ON-BOARD DIAGNOSTIC (OBD) SYSTEMCHECKThe On-Board Diagnostic (OBD) System Check is atroubleshootingmethod to find a problem caused by amalfunction in the electronic engine control system.It must be the starting point for any troubleshooting.See Figure 13.

The data shown in Table 1 can be used for compari-son after doing the troubleshooting checks and find-ing the on-board diagnostics working correctly with

no trouble codes shown. The data are an average ofdisplay values from normally operating vehicles andshow a display of a normally operating system.

After the visual/physical inspection, the On-BoardDiagnostic (OBD) System Check is the starting pointfor all troubleshooting procedures.

The correct procedure to find a problem is to followtwo basic steps.

1. Are the On-Board Diagnostics working? This isdetermined by doing the OBD System Check.Since this is the starting point for the trou-bleshooting procedures, always begin here.

2. Is there a Diagnostic Trouble Code? If thereis a DTC, go directly to the flowchart for thatDTC number. This determines if the fault is stillthere.

Test DescriptionThe numbers below are a reference to the numbersin bold in Figure 13.

1. The MIL should be ON steady with the ignitionON and the engine OFF. To isolate the malfunc-tion if the MIL does not light, refer to Figure 15.

2. Diagnostic Trouble Code (DTC) 12 means no rpmreference pulses from the ignition module. Thisis correct when engine is not running.

3. For list of valid DTCs, refer to the MSTS Diag-nostic Trouble Codes, Table 3. An invalid DTCmay be the result of a faulty MSTS.

4. If the engine does not start, refer to the trou-bleshooting diagram (Figure 18).

14


Figure 13. On-Board Diagnostic System Check

15

No Malfunction Indicator Lamp 2200 SRM 765

No Malfunction Indicator LampCIRCUIT DESCRIPTIONWhen the CodeMate Tester test switch is in theOFFposition and the CodeMate is plugged into the diag-nostic connector, the malfunction indicator lamp is

ON when the ignition is ON and engine is not run-ning. See Figure 14. The MSTS controls the lampand turns it ON by connecting it to ground throughpin 3B.

NOTE: THE NUMBER IN FRONT OF THE PIN DENOTES THE CONNECTOR. FOR EXAMPLE, 6D IS PIN D ONTHE 6-PIN CONNECTOR WHILE 5E IS PIN E ON THE 5-PIN CONNECTOR.

Figure 14. No Malfunction Indicator Lamp Circuit

TEST DESCRIPTIONThe numbers below are a reference to the numbersin bold in Figure 15.

1. This tests the circuits to the MSTS and diagnos-tic connector for voltage.

2. This tests the electronic driver circuit for themalfunction indicator lamp.

3. Test the CodeMate on another vehicle.

4. Test for an open circuit between wire harnessconnectors.

16

2200 SRM 765 No Malfunction Indicator Lamp

Figure 15. No Malfunction Indicator Lamp

17

No DTC-12, Malfunction Indicator Lamp ON 2200 SRM 765

No DTC-12, Malfunction Indicator Lamp ONCIRCUIT DESCRIPTIONWhen the CodeMate Tester switch is in the OFF po-sition and the CodeMate is plugged into the diag-nostic connector, the malfunction indicator lamp isON when the ignition is ON and engine is not run-ning. See Figure 16. The MSTS controls the lampand turns it ON by connecting it to ground throughpin 3B.

With the diagnostic connector pin B connected toground through pin A, the malfunction indicatorflashes a DTC-12, followed by any trouble codeskept in memory. A steady light means a short toground in the light control circuit between MSTSconnector pin 3B and diagnostic connector pin E, oran open circuit between MSTS connector pin 3C anddiagnostic connector pin B.


Figure 16. No DTC-12, Malfunction Indicator Lamp ON Circuit


1. If the malfunction indicator lamp is ON with theMSTS 3-pin connector disconnected, there may

be a short in the circuit between MSTS connec-tor pin 3B and diagnostic connector pin E. If thelamp is off, there may be a problem with eitherthe connector or the MSTS.

18

2200 SRM 765 Starter Rotates Engine, Engine Does Not Run

2. If the malfunction indicator is OFF, there is ashort between MSTS connector pin 3C and diag-nostic connector pin B.

3. If the problem is not fixed by Step 2, replace theMSTS.

Figure 17. No DTC-12, Malfunction Indicator Lamp ON

Starter Rotates Engine, Engine Does Not RunTEST DESCRIPTIONIf a tachometer has been connected to the TACHCONN., disconnect it before doing this test. See Fig-ure 18. The numbers below are a reference to thenumbers in bold in Figure 19.

1. Check a minimum of two spark plug wires tomake sure that one of the spark plug wire doesnot have an open circuit (Spark Tester ST-125).

19

Starter Rotates Engine, Engine Does Not Run 2200 SRM 765

Figure 18. Starter Rotates Engine, Engine Does Not Run Circuit

2. If a spark occurs when the electronic spark tim-ing (EST) connector is disconnected, the outputfrom the sensing coil is too low for EST opera-tion.

3. A spark indicates that the fault is in the distrib-utor cap or the rotor.

4. The normal voltage at the C and the + terminalsis battery voltage. A low voltage can indicate:

a. An open circuit or a high resistance circuitfrom the ignition switch to the distributor tothe ignition coil or

b. An open circuit in the primary winding of theignition coil.

If the voltage at C is less than battery voltage, andthere is 10 volts or more at +, there is an open circuitfrom C to the ignition coil or an open circuit in theprimary winding of the ignition coil.

5. Use the test light to check for a short circuit inthe ignition module. Check for approximately 12volts between the TACH CONN. and ground.

If the voltage is low (approximately 1 to 6 volts),there can be a fault in the ignition module. This

condition can cause a failure in the ignition coilfrom too much heat. If there is an open circuitin the primary winding of the ignition coil, a lowvoltage can leak through the ignition modulefrom the B+ to the TACH CONN. terminal.

6. The ignition module normally goes ON when 1.5to 8 volts is applied to terminal P from the sens-ing coil. When the ignition module is ON, thevoltage between the TACH CONN. and groundwill normally decrease to 7 to 9 volts. This testchecks if the sensing coil or the ignition modulehas a fault. When 1.5 to 8 volts is momentar-ily applied to terminal P, this voltage acts as atrigger voltage that replaces the voltage from thesensing coil. The procedure shows a test light,but any low voltage, low current source can beused as a trigger voltage.

7. When the momentary trigger voltage is removed,a spark is normally generated through the igni-tion coil. If no spark occurs, replace the ignitioncoil. If a spark occurs, check the sensing coil andthe rotating timer core.

20

2200 SRM 765 Starter Rotates Engine, Engine Does Not Run

Figure 19. Starter Rotates Engine, Engines Does Not Run (Sheet 1 of 2)

21

Starter Rotates Engine, Engine Does Not Run 2200 SRM 765

Figure 19. Starter Rotates Engine, Engines Does Not Run (Sheet 2 of 2)

22

2200 SRM 765 DTC-14 Engine Coolant Temperature (ECT) (Low Temperature Indicated)

DTC-14 Engine Coolant Temperature (ECT)(Low Temperature Indicated)

DTC-14 is set if the signal voltage indicates a coolanttemperature below 5 C ( 23 F) after the engineruns for three minutes.

CIRCUIT DESCRIPTIONThe Engine Coolant Temperature sensor (ECT) usesa thermistor to control the signal voltage to theMSTS module. See Figure 20. The MSTS module

applies a 5-volt reference voltage (terminal 6D) tothe ECT. When the engine coolant is cold, the ther-mistor resistance is higher than when the enginecoolant is at operating temperature. As the temper-ature of the engine coolant increases after the engineis started, the resistance decreases and the signalvoltage decreases. When the engine is operatingat 82 to 95 C (180 to 203 F), the signal voltage isapproximately 1.5 to 2.0 volts.


Figure 20. ECT Sensor Troubleshooting Circuit


1. This step determines if there is a fault in thewiring or the MSTS module or if the fault is inthe ECT.

2. Make sure the electrical connections do not havedirt and corrosion. If an ohmmeter is connectedacross terminals A and B of the ECT, the resis-tance normally decreases as the temperature ofthe engine coolant increases.

3. This step checks if there is a fault in the wiringto the ECT or the sensor ground.

23

DTC-14 Engine Coolant Temperature (ECT) (Low Temperature Indicated) 2200 SRM 765

Figure 21. ECT Sensor Troubleshooting Diagram (Low Temperature)

24

2200 SRM 765 DTC-15 Engine Coolant Temperature Sensor (ECT) (High Temperature Indicated)

DTC-15 Engine Coolant Temperature Sensor (ECT)(High Temperature Indicated)

DTC-15 is set if the signal voltage indicates a coolanttemperature above 135 C (275 F) for three seconds.

CIRCUIT DESCRIPTIONThe Engine Coolant Temperature sensor (ECT) usesa thermistor to control the signal voltage to theMSTS module. See Figure 22. The MSTS moduleapplies a 5-volt reference voltage (terminal 6D) to

the ECT. When the engine coolant is at operatingtemperature, the thermistor resistance is lower thanwhen the engine coolant is cold. As the temperatureof the engine coolant increases after the engine isstarted, the resistance decreases and the signalvoltage decreases. When the engine is operatingat 82 to 95 C (180 to 203 F), the signal voltage isapproximately 1.5 to 2.0 volts.


Figure 22. ECT Sensor Troubleshooting Circuit


1. This step determines if there is a fault in thewiring or the MSTS module or if the fault is inthe ECT.

2. Make sure the electrical connections do not havedirt and corrosion. If an ohmmeter is connectedacross the terminals A and B of the ECT, the re-sistance normally decreases as the temperatureof the engine coolant increases.

25

DTC-15 Engine Coolant Temperature Sensor (ECT) (High Temperature Indicated) 2200 SRM 765

Figure 23. ECT Sensor Troubleshooting Diagram (High Temperature)

26

2200 SRM 765 DTC-34 Manifold Absolute Pressure (MAP) Sensor

DTC-34 Manifold Absolute Pressure (MAP) SensorCIRCUIT DESCRIPTIONWhen the load on the engine changes, the pressurein the intake manifold changes. See Figure 24. Thispressure is less than the atmospheric pressure. TheManifold Absolute Pressure (MAP) sensor measuresthe changes in the intake manifold pressure and con-verts these changes to a voltage signal. The MSTSmodule sends a reference signal (5.0 volts) to theMAP sensor. When the manifold pressure changes,the electrical signal of the MAP sensor changes andthe signal is received by the MSTS module.

When the engine is at idle speed and does not havea load on it, the normal signal voltage from the MAP

sensor is approximately 1.0 volt. When the throttlevalve is fully opened, the intake manifold pressure ishigher (less vacuum) and the signal voltage from theMAP sensor is approximately 4.5 volts.

When the ignition switch is turned to ON, the ini-tial voltage signal from the MAP sensor indicatesthe barometric pressure (BARO signal) to the MSTSmodule. The MSTS module remembers the baromet-ric pressure (BARO signal) after the engine is run-ning. The MSTS module then automatically adjuststhe ignition timing for different altitudes and atmo-spheric conditions.

NOTE: THE NUMBER IN FRONT OF THE PIN DENOTES THE CONNECTOR. FOR EXAMPLE, 6C IS PIN C ONTHE 6-PIN CONNECTOR WHILE 5E IS PIN E ON THE 5-PIN CONNECTOR.

Figure 24. MAP Sensor Troubleshooting Circuit


1. This step determines if there is adequate vacuumsupply to the MAP sensor.

2. This step checks for the 5-volt reference signal inthe MAP sensor harness connection.

3. This step checks for an open circuit from pin A toground or an open or shorted wire between pin Cand pin 6F. See Figure 24.

4. These steps are checking the MAP signal circuitfor faults.

5. Low manifold vacuum may result from a restric-tion in the MAP sensor hose or from vacuumleaks in the engine air intake system.

27

DTC-34 Manifold Absolute Pressure (MAP) Sensor 2200 SRM 765

Figure 25. MAP Sensor Troubleshooting Diagram (Sheet 1 of 2)

28

2200 SRM 765 DTC-34 Manifold Absolute Pressure (MAP) Sensor

Figure 25. MAP Sensor Troubleshooting Diagram (Sheet 2 of 2)

29

DTC-41 Electronic Spark Timing (EST) Open Circuit 2200 SRM 765

DTC-41 Electronic Spark Timing (EST) Open CircuitDTC-41 is set if there is an open circuit in the elec-tronic spark timing circuit.

CIRCUIT DESCRIPTIONWhen the system is running on the ignition module,there is no voltage on the bypass wire and the igni-tion module grounds the EST signal. See Figure 26.If the MSTS senses a voltage on the EST circuit, a

Code 41 is set and the MSTS does not go into the ESToperation mode.

If the bypass wire is open or grounded, the ignitionmodule does not change to EST mode, and a Code 42is indicated.

If the EST circuit has a short circuit to ground, thereis no EST signal, and a Code 42 is indicated.

Figure 26. EST Troubleshooting, Open Circuit


1. A Code 41 is indicated if there is an open circuitin the EST circuit. This test determines if theCode 41 is a real fault.

2. This test checks that the ground path throughthe ignition module is correct. A short circuitfrom MSTS connector pin 6B to ground also in-dicates less than 500 Ohms.

30

2200 SRM 765 DTC-41 Electronic Spark Timing (EST) Open Circuit

Figure 27. DTC-41 Troubleshooting Diagram

31

DTC-42 Electronic Spark Timing (EST) Grounded Circuit 2200 SRM 765

DTC-42 Electronic Spark Timing (EST) Grounded CircuitA DTC 42 is set if the EST circuit is grounded or ifthere is an open circuit or a short circuit in the bypasscircuit.

CIRCUIT DESCRIPTIONWhen the system is running on the ignition module,there is no voltage on the bypass wire and the igni-tion module grounds the EST signal. See Figure 28.If the MSTS senses a voltage on the EST circuit, aCode 41 is set and the MSTS does not go into the ESTmode.

When the engine is being started and approximately400 rpm is sensed, bypass voltage is applied by theMSTS. The EST circuit is no longer grounded in theignitionmodule and the EST circuit voltage normallyhas a variation during operation.

If the bypass wire is open or grounded, the ignitionmodule will not change to EST mode and a Code 42is indicated.

If the EST circuit has a short circuit to ground, thereis no ignition signal and a Code 42 is indicated.

Figure 28. EST Troubleshooting, Grounded Circuit


1. A Code 42 is indicated if there is an open circuitor a short circuit in the bypass circuit or if theEST circuit is grounded. This test determines ifthe Code 42 is a real fault.

2. This test checks that the ground path throughthe ignition module is correct.

3. This test checks to see if the IC module makesthe switch in resistance.

4. This test checks for short circuits to ground inthe EST circuit, opens in the bypass circuit, andfaulty connections in the IC module.

32

2200 SRM 765 DTC-42 Electronic Spark Timing (EST) Grounded Circuit

Figure 29. DTC-42 Troubleshooting Diagram

33

Distributor Repair 2200 SRM 765

DTC-51 MSTS FailureCIRCUIT DESCRIPTIONThe Electronic ControlModule (MSTS) does an inter-nal check. If the internal check fails, the MSTS setsDTC 51.

The number below is a reference to the number inbold in Figure 30.

1. This step checks the MSTS. If a Code-51 isset and all connections are correct, replace theMSTS.

Figure 30. MSTS Failure

Distributor RepairA distributor with a separate ignition coil is used onall MSTS engines. The ignition coil is connected tothe rotor in the distributor through a high-voltagewire. The operation of the ignition module and themagnetic pulse generator is described under Opera-tion at the beginning of this section.

When the current in the primary circuit of the ig-nition coil quickly decreases, the induction in thesecondary circuit sends a high voltage pulse (35,000volts) to the rotor in the distributor. The rotor isaligned with one of the leads to a spark plug wireand this high voltage pulse is sent to one of the sparkplugs.

REMOVE

CAUTIONCarefully lift and release lock tabs on connec-tors to distributor. Lock tabs can be easily bro-ken if too much force is applied with a screw-driver or other tool.

Never permit TACH CONN. terminal to touchground. Ignition module or ignition coil can bedamaged.

1. Disconnect battery negative (ground) cable.

2. If removal of the spark plug wires is not requiredfor the repairs, leave them connected to distrib-utor cap. Remove two capscrews that fasten dis-tributor cap to distributor. Move distributor capaway from work area.

34

2200 SRM 765 Distributor Repair

3. Disconnect distributor 4-terminal connector.

4. Disconnect ignition coil connector.

5. Remove bolt and clamp that hold distributor inengine. Make a note of the positions of rotorto distributor housing and distributor to engine.Slowly pull distributor from engine until rotorjust stops turning counterclockwise and make anote of the position of rotor. This position mustbe used when distributor is installed again.

DISASSEMBLE1. Remove rotor. See Figure 31. Make a match

mark on gear and shaft so they can be assembledin the same position.

1. CAP2. ROTOR3. SHAFT/TIMER

CORE4. RETAINER5. SHIELD6. COIL7. POLE PIECE

8. IGNITION MODULE9. ALIGNMENT PIN10. HOUSING11. WASHER12. SEAL13. DRIVE GEAR14. ROLL PIN15. GASKET

Figure 31. Distributor

2. Use a punch to remove roll pin from shaft.

3. Remove gear.

4. Remove shaft with timer core from housing.

5. Remove retainer from housing. Use a screw-driver as a prybar.

6. Disconnect sensing coil from ignition module.

CAUTIONCarefully lift and release lock tab on connectorto sensing coil. Lock tab can be easily brokenif too much force is applied with a screwdriveror other tool.

7. Use a screwdriver to lift lock tab. Remove sens-ing coil.

8. Remove two screws that hold ignition module inhousing. Remove ignition module.

INSPECTInspect shaft for a loose fit between shaft and itsbushing in housing. If bushing or shaft is worn sothat shaft moves from side to side in bushing, replaceshaft or housing.

Inspect housing for cracks or damage.

ASSEMBLE1. Apply silicon grease to bottom of ignition module.

See Figure 31. Install ignition module into hous-ing and tighten two screws.

NOTE: Hyster Part No. 304408 is a silicon bearinggrease used between electronic components and theirheat sinks. A small container of silicon grease is en-closed in the package with a new ignition module.

2. Install sensing coil. Tab on bottom of sensing coilfits into anchor hole in housing.

3. Connect sensing coil to ignition module. Makesure that lock tab on connector is fastened.

4. Install shield.

5. Install retainer.

6. Install shaft assembly into housing.

7. Install washer and seal on housing.

8. Install gear on end of shaft.

9. Align marks on gear and shaft. Install roll pin.Turn shaft assembly and make sure teeth oftimer core on shaft assembly do not touch polepiece.

35

Distributor Repair 2200 SRM 765

10. Install gasket on gear.

11. Install rotor on shaft.

INSTALL1. Put rotor and distributor in the same position as

it was removed from engine.

If engine has been rotated after distributor wasremoved, the following procedure must be usedbefore distributor is installed again:

a. Remove No. 1 spark plug.

b. Put a finger over No. 1 spark plug hole andslowly rotate engine until pressure is felt oncompression stroke.

c. Align timing mark on crankshaft pulley to 0(TDC) on engine timing indicator.

d. Turn distributor rotor to point between posi-tions on distributor cap for No. 1 and No. 4spark plug leads.

e. Install distributor in engine. Rotor and shaftwill rotate a few degrees when gear on dis-tributor shaft engages drive gear on enginecam. Timing is correct if rotor points at theposition on distributor cap for No. 1 sparkplug lead.

2. Install clamp and bolt. Tighten bolt with yourhand.

3. Install distributor 4-terminal connector.

4. Install ignition coil connector.

5. Install distributor cap and two capscrews. Ifspark plug wires were removed, install them incorrect sequence.

6. Connect battery negative cable.

7. Start engine and check engine timing. See thefollowing paragraphs about Ignition Timing.

8. Tighten bolt for distributor clamp to 43 Nm(31.7 lbf ft).

IGNITION TIMING

WARNINGDo not touch moving parts (fan, belt, shafts,pulleys).

To check the initial ignition timing set point, do thefollowing.

1. Warm engine to normal operating temperature.

2. Turn engines ignition switch to OFF position.

3. Make sure that CodeMate test switch is in OFFposition.

4. Plug CodeMate into diagnostic connector in en-gine compartment.

5. Place CodeMate test switch in ON position andstart engine.

6. Check initial timing set point with a timing light.The correct setting for initial timing set point is8 BTDC for 3.0L engine and 0 TDC for 4.3Lengine.

7. If timing is not correct, loosen clamp that holdsdistributor housing. Rotate housing right or leftto get correct timing. Tighten clampwhen timingis correct.

8. Turn ignition key to OFF position.

9. Remove CodeMate Tester from diagnostic con-nector and place diagnostic connector into pro-tective cover.

36

2200 SRM 765 Ignition Module Repair

Ignition Module RepairTEST FOR FAULTNOTE: The ignition module can be checked in thedistributor. A test light and three jumper wires areneeded to make the tests. The battery in the vehiclemust be fully charged so that the starter rotates theengine at the normal speed.

1. Disconnect 4-terminal connector from distrib-utor. See Figure 32. Use two jumper wiresbetween distributor and 4-terminal connector toconnect the following circuits:

REFERENCE (pin C)GROUND (pin A)

2. Connect test light to a 12-volt positive source.Start engine. Touch probe of test light to pin Bin 4-terminal connector on distributor. When 12volts are applied through test light to pin B (BY-PASS), ignition module changes to EST mode.The EST connection (pin D) is open and enginewill normally stop. This step checks the BYPASSoperation of the ignition module.

Figure 32. Ignition System Troubleshooting

3. Use a jumper to connect pin D (EST) to pin C(REFERENCE) at distributor. Apply 12 voltsthrough test light to pin B (BYPASS) as describedin Step 2. Start engine. If engine starts, thisstep checks that EST circuit in ignition moduleis good.

4. Remove test light from pin B (BYPASS) while en-gine is running. If engine stops, this check showsthat ignition module internally changes EST cir-cuit to ground. Since there is a jumper wire be-tween pin D (EST) to pin C (REFERENCE), the

REFERENCE signal is also sent to ground andengine stops.

5. If any tests described in Step 2, Step 3, or Step 4do not work as indicated, check wiring harnessfor a short circuit or an open circuit. If wiringharness is good, replace ignition module.

6. When the tests are complete, connect system fornormal operation.

37

Sensing Coil Repair 2200 SRM 765

REPLACE1. Remove distributor cap and rotor.

2. Remove two screws that hold ignition module indistributor.

3. Lift ignition module and disconnect connections.Make a note of the connections so that they canbe correctly connected again. Remove ignitionmodule from distributor.

NOTE: Do not remove silicon grease from ignitionmodule or distributor if the same ignitionmodule willbe installed again. If a new ignition module is in-stalled, a small container of silicon grease is in the

package. Clean old silicon grease and apply a newlayer of silicon grease to ignition module and dis-tributor housing. This silicon grease is necessary forcooling the ignition module.

4. Connect connectors in distributor to ignitionmodule. Make sure connectors are the same aswhen they were removed.

5. Install ignition module in distributor.

6. Install two screws that fasten ignition module indistributor.

7. Install distributor cap and rotor.

Sensing Coil RepairTEST FOR FAULT1. Disconnect battery negative cable.

2. Remove distributor cap. Disconnect connectionfrom sensing coil to ignition module.

3. Check resistance of sensing coil with an ohmme-ter. Connect ohmmeter to sensing coil connec-tions as shown in step 1 of Figure 33. Check re-sistance between both connections and ground.Ohmmeter will indicate infinity for both connec-tions, if sensing coil is good.

4. Connect ohmmeter across both sensing coil con-nections as shown in step 2 of Figure 33. If ohm-meter does not indicate 500 to 1500 ohms, re-place sensing coil. Check wires for a loose con-nection.

REPLACERemove and disassemble distributor as described inDistributor Repair.

A. STEP 1 B. STEP 2

1. SENSING COILCONNECTIONS

2. OHMMETER

Figure 33. Test Sensing Coil

38

2200 SRM 765 Ignition Coil Repair

Ignition Coil RepairTEST FOR FAULT1. Disconnect battery negative (ground) cable.

2. Disconnect high voltage wire.

3. Disconnect connectors at ignition coil.

4. Set ohmmeter on one of the higher scales. Con-nect ohmmeter as shown in step 1 of Figure 34. Ifohmmeter indication is less than infinity, installa new ignition coil.

A. STEP 1B. STEP 2

C. STEP 3

1. CLEAN METALFOR GROUNDCONNECTION

2. OHMMETER

3. C AND TACHCONNECTOR

4. B AND +TERMINALS

Figure 34. Ignition Coil

5. Set ohmmeter on one of the low scales. Connectohmmeter as shown in step 2 of Figure 34. Ifohmmeter indication is greater than one ohm, in-stall a new ignition coil.

6. Set ohmmeter on one of the middle scales. Con-nect ohmmeter as shown in step 3 of Figure 34.If ohmmeter indication is infinity (open circuit),install a new ignition coil.

REMOVE1. Turn key switch to OFF. Apply parking brake.

2. Disconnect negative battery cable.

3. Put tags for identification on connectors and dis-connect them from coil.

CAUTIONDo not damage high voltage wires (spark plugwires) during removal. Hold wire by boot nearend of wire. Rotate boot before pulling it andconnection from terminal.

4. Remove high voltage wires.

5. Remove nuts (or capscrews) that fasten bracketfor ignition coil to engine.

6. Remove ignition coil and bracket assembly fromengine.

7. Use a drill and punch to remove two rivets thatfasten bracket to coil.

INSTALL1. Install original bracket on replacement coil using

screws (supplied with replacement coil).

2. Install ignition coil assembly on engine with nuts(or capscrews).

3. Install control wire connectors and high voltagewire on ignition coil.

4. Connect negative (ground) battery cable.

39

ECT Sensor Replacement 2200 SRM 765

MSTS Module RepairNOTE: See the TROUBLESHOOTING descriptionsto check the operation of the MSTS module. The fol-lowing paragraphs describe the removal and instal-lation of the MSTS module.

REMOVE

CAUTIONNever connect or disconnect wiring harness atMSTS module when key switch is ON. Neverconnect jumper wires or test instruments toMSTS module when key switch is ON. The bestprocedure is to disconnect battery negativecable when removing or installing electricalcomponents.

Do not touch connector pins. MSTSmodule canbe damaged with an electrostatic discharge.

MSTS connector locations and mounting holes areshown in Figure 35.

1. Disconnect battery negative cable. Disconnectthree connectors at MSTS module.

2. Remove two bolts that fastenMSTSmodule to itsmount. Remove MSTS module.

INSTALL1. Install MSTS module on its mount surface and

install two bolts.

2. Connect three connectors at MSTS module. Con-nect battery negative cable.

Figure 35. MSTS Module

ECT Sensor ReplacementWARNING

The coolant can be very hot. Use caution toprevent personal injury.

NOTE: See the TROUBLESHOOTING descriptionsto check the operation of the ECT sensor. The fol-lowing paragraphs describe the disconnection or theremoval and installation of the ECT sensor.

1. Disconnect battery negative cable. Disconnectconnector at ECT sensor. See Figure 36.

2. Use a wrench and carefully loosen ECT fromcoolant manifold.

3. Use a liquid sealant on threads and install ECTin its hole in coolant manifold and carefullytighten it with a wrench.

4. Connect connector at ECT. Connect battery neg-ative cable.

5. Fill radiator with coolant as required.

1. TEMPERATURE SENSOR2. ELECTRICAL CONNECTOR3. LOCK TAB

Figure 36. Engine Coolant Temperature Sensor(ECT)

40

2200 SRM 765 MAP Sensor Replacement

MAP Sensor ReplacementNOTE: The MAP sensor is on the bracket that is ontop of the valve cover.

1. Disconnect battery negative cable. Disconnectvacuum hose from MAP sensor. Disconnect elec-trical connector at MAP sensor. See Figure 37.

2. Remove screws that fasten MAP to its mount.Remove MAP sensor.

3. Install MAP sensor on its mount surface and in-stall screws.

4. Connect electrical connector at MAP sensor.Connect vacuum hose to MAP sensor. Connectbattery negative cable.

1. SENSOR2. ELECTRICAL CONNECTOR

Figure 37. Manifold Absolute Pressure (MAP)Sensor

41

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42

TECHNICAL PUBLICATIONS

2200 SRM 765 11/01 (11/99) Printed in U.S.A.

tocMicroprocessor Spark Timing System (MSTS)Safety Precautions Maintenance and RepairGeneralDescriptionWhat MSTS DoesHow MSTS Begins Operation

OperationDistributorIgnition CoilIgnition ModuleWhen Engine Is Being StartedWhen Engine Is RunningManifold Absolute Pressure (MAP) SensorEngine Coolant Temperature (ECT) SensorMSTS Module Corrections

TroubleshootingGeneralTools and Test EquipmentMSTSTroubleshooting ProcedureWhere to StartVisual/Physical InspectionKnowledge/Tools RequiredDamage from Static Discharge (Static Electricity)

Troubleshooting InformationMalfunction Indicator Lamp (MIL)Connecting CodeMate TesterReading Diagnostic Trouble Codes (DTC)Clearing Diagnostic Trouble Codes (DTC's)

On-Board Diagnostic (OBD) System CheckTest Description

No Malfunction Indicator LampCircuit DescriptionTest Description

No DTC-12, Malfunction Indicator Lamp ONCircuit DescriptionTest Description

Starter Rotates Engine, Engine Does Not RunTest Description

DTC-14 Engine Coolant Temperature (ECT) (Low Temperature IndicatCircuit DescriptionTest Description

DTC-15 Engine Coolant Temperature Sensor (ECT) (High TemperatureCircuit DescriptionTest Description

DTC-34 Manifold Absolute Pressure (MAP) SensorCircuit DescriptionTest Description

DTC-41 Electronic Spark Timing (EST) Open CircuitCircuit DescriptionTest Description

DTC-42 Electronic Spark Timing (EST) Grounded CircuitCircuit DescriptionTest Description

DTC-51 MSTS FailureCircuit Description

Distributor RepairRemoveDisassembleInspectAssembleInstallIgnition Timing

Ignition Module RepairTest For FaultReplace

Sensing Coil RepairTest For FaultReplace

Ignition Coil RepairTest For FaultRemoveInstall

MSTS Module RepairRemoveInstall

ECT Sensor ReplacementMAP Sensor Replacement

tablesTable 1. MSTS Module ConnectionsTable 2. Pressure Conversion ChartTable 3. MSTS Diagnostic Codes

msts ignition system

Documents

unit clean

unit whenmaking repairs

unit needs repairs

working area clean

safety information

safety precautionsmaintenance

tools clean

heavy parts