TABLE OF CONTENTS
1.0 INTRODUCTION.........................................................1
1.1SYSTEM COVERAGE..............................................1
1.2SIX-STEP TROUBLESHOOTING PROCEDURE.........................1
2.0 IDENTIFICATION OF SYSTEM.............................................1
3.0 SYSTEM DESCRIPTION AND FUNCTIONAL OPERATION......................1
3.1GENERAL DESCRIPTION...........................................1
3.2FUNCTIONAL OPERATION..........................................2
3.2.1ECM On-Board Diagnostics....................................2
3.2.2ECM Operating Modes........................................2
3.2.3Monitored Circuits............................................3
3.2.4SKIS On-Board Diagnostics....................................3
3.2.5SKIS Overview...............................................3
3.2.6SKIS Operation..............................................3
3.3DIAGNOSTIC TROUBLE CODES.....................................4
3.3.1Hard Code..................................................4
3.3.2Intermittent Code.............................................5
3.3.3Reset Counter...............................................5
3.3.4ECM Diagnostic Trouble Codes.................................5
3.3.5SKIM Diagnostic Trouble Codes.................................7
3.3.6Handling No Trouble Code Problems.............................7
3.4USING THE DRB..................................................7
3.5DRB ERROR MESSAGES AND BLANK SCREEN........................7
3.5.1DRB Does Not Power Up......................................8
3.5.2Display is Not Visible..........................................8
4.0 SYSTEM COMPONENT LOCATIONS........................................9
4.1ENGINE CONTROL MODULE........................................9
4.2CONTROLS AND SOLENOIDS......................................10
4.3DATA LINK CONNECTOR..........................................10
4.4SENSORS.......................................................11
4.6RELAYS........................................................13
4.7SWITCHES......................................................15
4.8LAMPS AND INDICATORS.........................................17
5.0 DISCLAIMERS, SAFETY, WARNINGS......................................17
5.1DISCLAIMERS....................................................17
5.2SAFETY.........................................................17
5.2.1Technician Safety Information..................................17
5.2.2Vehicle Preparation for Testing.................................17
5.2.3Servicing Sub-Assemblies.....................................17
5.2.4DRBIIITSafety Information....................................17
5.3WARNINGS......................................................18
5.3.1Vehicle Damage Warnings....................................18
5.3.2Road Testing a Complaint Vehicle..............................18
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TABLE OF CONTENTS - Continued
7.0 DIAGNOSTIC INFORMATION AND PROCEDURES...........................19
7.1GENERAL TROUBLESHOOTING....................................19
TROUBLE CODE TESTS
TEST DTCCHECKING FOR DIAGNOSTIC TROUBLE CODES.............20
TC-1AREPAIRING - A/C CONTROL SHORT CIRCUIT.................22
TC-2AREPAIRING - A/C CONTROL OPEN CIRCUIT..................28
TC-3AREPAIRING - A/C SYSTEM PRESSURE SIGNAL HIGH
EXCEEDED..............................................34
TC-4AREPAIRING - A/C SYSTEM PRESSURE SIGNAL LOW
EXCEEDED..............................................38
TC-5AREPAIRING - A/C SYSTEM PRESSURE SUPPLY HIGH
EXCEEDED..............................................42
TC-6AREPAIRING - A/C SYSTEM PRESSURE SUPPLY LOW
EXCEEDED..............................................46
TC-7AREPAIRING - ACCELERATOR PEDAL SENSOR TROUBLE
CODES.................................................50
TC-14AREPAIRING - BATTERY VOLTAGE SRC HIGH EXCEEDED.......60
TC-15AREPAIRING - TURBOCHARGER BOOST SENSOR SIGNAL HIGH
EXCEEDED..............................................62
TC-16AREPAIRING - TURBOCHARGER BOOST SENSOR SIGNAL LOW
EXCEEDED..............................................70
TC-17AREPAIRING - TURBOCHARGER BOOST SENSOR SUPPLY HIGH
EXCEEDED..............................................74
TC-18AREPAIRING - TURBOCHARGER BOOST SENSOR SUPPLY LOW
EXCEEDED..............................................78
TC-19AREPAIRING - TURBOCHARGER BOOST SENSOR PLAUSIBILITY.82
TC-20AREPAIRING - BRAKE SWITCH PLAUSIBILITY WITH REDUNDANT
CONTACT...............................................86
TC-21AREPAIRING - CLUTCH SIGNAL PLAUSIBILITY.................94
TC-22AREPAIRING - CONTROL SLEEVE SENSOR SIGNAL HIGH
EXCEEDED..............................................98
TC-23AREPAIRING - CONTROL SLEEVE SENSOR START END POSITION
NOT ATTAINED..........................................102
TC-24AREPAIRING - CONTROL SLEEVE SENSOR STOP END POSITION
NOT ATTAINED..........................................104
TC-25AREPAIRING - CRUISE STATUS INDICATOR LAMP SHORT
CIRCUIT................................................106
TC-26AREPAIRING - DIAGNOSTIC LAMP OPEN CIRCUIT............110
TC-27AREPAIRING - DIAGNOSTIC LAMP SHORT CIRCUIT...........114
TC-30AREPAIRING - DIESEL POWER RELAY SHUTS OFF TOO EARLY .118
TC-31AREPAIRING - DIESEL POWER RELAY SHUTS OFF TOO LATE . .122
TC-33AREPAIRING - EGR OPEN CIRCUIT.........................126
TC-34AREPAIRING - EGR SHORT CIRCUIT........................130
TC-35AREPAIRING - ENGINE SPEED SENSOR DYNAMIC
PLAUSIBILITY...........................................134
TC-36AREPAIRING - ENGINE SPEED SENSOR OVERSPEED
RECOGNITION..........................................138
TC-38AREPAIRING - ENGINE SPEED SENSOR STATIC PLAUSIBILITY .140
TC-39AREPAIRING - FAN CONTROL OPEN CIRCUIT FAN 1..........144
TC-40AREPAIRING - FAN CONTROL OPEN CIRCUIT FAN 2..........148
TC-41AREPAIRING - FAN CONTROL SHORT CIRCUIT FAN 1.........152
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TC-42AREPAIRING - FAN CONTROL SHORT CIRCUIT FAN 2.........156
TC-43AREPAIRING - FUEL QUANTITY ACTUATOR NEG. GOVERNOR
DEVIATION COLD.......................................160
TC-44AREPAIRING - FUEL QUANTITY ACTUATOR NEG. GOVERNOR
DEVIATION WARM.......................................164
TC-45AREPAIRING - FUEL QUANTITY ACTUATOR POS. GOVERNOR
DEVIATION COLD.......................................168
TC-46AREPAIRING - FUEL QUANTITY ACTUATOR POS. GOVERNOR
DEVIATION WARM.......................................172
TC-47AREPAIRING - FUEL TEMPERATURE SENSOR SRC HIGH
EXCEEDED.............................................176
TC-48AREPAIRING - FUEL TEMPERATURE SENSOR SRC LOW
EXCEEDED.............................................180
TC-51AREPAIRING - GLOW RELAY #1 CONTROLLER OPEN CIRCUIT .184
TC-52AREPAIRING - GLOW RELAY #2 CONTROLLER OPEN CIRCUIT .188
TC-53AREPAIRING - GLOW RELAY #1 CONTROLLER SHORT
CIRCUIT................................................192
TC-54AREPAIRING - GLOW RELAY #2 CONTROLLER SHORT
CIRCUIT................................................196
TC-56AREPAIRING - INDUCTIVE AUXILIARY SPEED SENSOR DYNAMIC
PLAUSIBILITY...........................................200
TC-57AREPAIRING - INDUCTIVE AUXILIARY SPEED SENSOR
OVERSPEED RECOGNITION..............................204
TC-58AREPAIRING - INDUCTIVE AUXILIARY SPEED SENSOR
PLAUSIBILITY...........................................208
TC-59AREPAIRING - INDUCTIVE AUXILIARY SPEED SENSOR STATIC
PLAUSIBILITY...........................................212
TC-62AREPAIRING - INTAKE AIR TEMPERATURE SENSOR SIGNAL HIGH
EXCEEDED.............................................216
TC-63AREPAIRING - INTAKE AIR TEMPERATURE SENSOR SIGNAL LOW
EXCEEDED.............................................220
TC-72AREPAIRING - NEEDLE MOVEMENT SENSOR SRC HIGH
EXCEEDED.............................................224
TC-73AREPAIRING - NEEDLE MOVEMENT SENSOR SRC LOW
EXCEEDED.............................................228
TC-74AREPAIRING - REDUNDANT EMERGENCY STOP PLAUSIBILITY IN
AFTER-RUN............................................232
TC-75AREPAIRING - REDUNDANT EMERGENCY STOP POWERSTAGE
DEFECTIVE.............................................236
TC-76AREPAIRING - SMART START RELAY SHORT CIRCUIT.........240
TC-79AREPAIRING - SOLENOID VALVE CONTROLLER OPEN
CIRCUIT................................................242
TC-80AREPAIRING - SOLENOID VALVE CONTROLLER SHORT
CIRCUIT................................................246
TC-81AREPAIRING - TEMPERATURE OF ENGINE COOLANT SRC HIGH
EXCEEDED.............................................250
TC-82AREPAIRING - TEMPERATURE OF ENGINE COOLANT SRC LOW
EXCEEDED.............................................254
TC-84AREPAIRING - TERMINAL 15 PLAUSIBILITY AFTER START-UP . . .258
TC-85AREPAIRING - TIMING GOVERNING NEGATIVE GOVERNOR
DEVIATION.............................................262
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TABLE OF CONTENTS - Continued
TC-86AREPAIRING - TIMING GOVERNING POSITIVE GOVERNOR
DEVIATION.............................................266
TC-91AREPAIRING - VEHICLE SPEED SENSOR TROUBLE CODES. . . .270
TC-94AREPAIRING - VEHICLE THEFT ALARM TROUBLE CODES......280
SENTRY KEY IMMOBILIZER SYSTEM
SK-1AIDENTIFYING SENTRY KEY IMMOBILIZER PROBLEMS........286
SK-2AREPAIRING - PCM STATUS FAILURE.......................290
SK-3AREPAIRING - ROLLING CODE FAILURE.....................294
SK-4AREPAIRING - SERIAL LINK EXTERNAL FAILURE..............298
SK-5AREPAIRING - TRANSPONDER COMMUNICATION FAILURE.....302
SK-6ATRANSPONDER CRC (CYCLIC REDUNDANCY CHECK)
FAILURE...............................................306
SK-7AREPAIRING - TRANSPONDER ID MISMATCH................310
SK-8AREPAIRING - TRANSPONDER RESPONSE MISMATCH........314
SK-9AREPAIRING - VIN MISMATCH..............................318
NO TROUBLE CODE TESTS
NTC-1ANO TROUBLE CODE TEST MENU..........................322
NTC-2ACHECKING GLOW PLUG OPERATION......................324
NTC-3ACHECKING FUEL INJECTION PUMP CIRCUITS...............328
NTC-4ACHECKING THE PCM POWER AND GROUNDS..............330
NTC-5ACHECKING ENGINE COOLANT SENSOR CALIBRATION AND
RADIATOR FAN OPERATION..............................332
NTC-6ACHECKING ACCELERATOR PEDAL POSITION SENSOR
CALIBRATION...........................................334
NTC-7ACHECKING BOOST PRESSURE SENSOR CALIBRATION.......336
NTC-8ACHECKING FUEL TEMPERATURE SENSOR CALIBRATION.....338
NTC-9ACHECKING EGR SYSTEM.................................340
NTC-10ACHECKING THE FUEL HEATER AND THE CRANKCASE VENT
HEATER................................................342
NTC-11ACHECKING RADIATOR FAN OPERATION....................352
NTC-12ACHECKING THE ENGINE MECHANICAL SYSTEMS...........366
NTC-13ACHECKING THE TURBOCHARGER OPERATION..............368
SPEED CONTROL TESTS
SC-1ACHECKING SPEED CONTROL OPERATION..................372
SC-2ACHECKING SPEED CONTROL OPERATION..................376
SC-3ACHECKING SPEED CONTROL OPERATION..................378
SC-4ACHECKING SPEED CONTROL OPERATION..................386
SC-5ACHECKING SPEED CONTROL OPERATION..................388
SC-6ACHECKING CRUISE INDICATOR OPERATION................390
NO START TESTS
NS-SELNO START SELECTION MENU.............................392
NS-1AREPAIRING A NO CRANK CONDITION......................394
NS-2AREPAIRING A NO RESPONSE CONDITION..................400
NS-3AREPAIRING - NO START..................................410
NS-4AREPAIRING A START AND STALL CONDITION................418
NS-5ACHECKING THE ENGINE MECHANICAL SYSTEMS...........420
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TABLE OF CONTENTS - Continued
VERIFICATION TEST
VER-1ANO START VERIFICATION................................422
VER-2AROAD TEST VERIFICATION...............................423
VER-3ASPEED CONTROL VERIFICATION..........................424
8.0 MAINTENANCE AND SERVICE INFORMATION.............................425
8.1PROGRAMMING THE ENGINE CONTROL MODULE...................425
8.2PROGRAMMING THE BODY CONTROL MODULE.....................425
8.3PROGRAMMING THE SENTRY KEY IMMOBILIZER MODULE...........426
8.4PROGRAMMING IGNITION KEYS TO THE SENTRY KEY IMMOBILIZER
MODULE.......................................................426
10.0 SCHEMATIC DIAGRAM.................................................427
11.0 REQUIRED TOOLS AND EQUIPMENT....................................428
12.0 GLOSSARY OF TERMS.................................................428
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1.0 INTRODUCTION
The procedures contained in this manual include all the specifications, instructions, and graphics
needed to diagnose engine control module (ECM) and sentry key immobilizer system (SKIS)
problems; they are no start, diagnostic trouble code, and no trouble code problems for the ECM.
The diagnostics in this manual are based on the trouble condition or symptom being present at
the time of diagnosis.
When repairs are required, refer to the appropriate volume of the service manual for proper
removal and repair procedure.
Diagnostic procedures change every year. New diagnostic systems may be added; carryover
systems may be enhanced. IT IS RECOMMENDED THAT YOU REVIEW THE ENTIRE MANUAL
TO BECOME FAMILIAR WITH ALL NEW AND CHANGED DIAGNOSTIC PROCEDURES.
This manual is designed to begin all diagnosis at the DTC TEST, which is located at the beginning
of Section 7.1. This will cover all the necessary requirements to begin a logical diagnostic path for
each problem. If there is a diagnostic trouble code (DTC) detected, it will direct you to the trouble
code test. If there are no trouble codes present, it will direct you by symptom to a no-trouble code
test.
This book reflects many suggested changes from readers of past issues. After using this book, if
you have any comments or recommendations, please fill out the form at the back of the book and
mail it back to us.
1.1 System Coverage
This diagnostic procedures manual covers all 2000 GS body equipped with the 2.5L VM diesel
engine.
1.2 Six-Step Troubleshooting Procedure
Diagnosis of the engine control module (ECM) and SKIS is done in six basic steps:
²verification of complaint
²verification of any related symptoms
²symptom analysis
²problem isolation
²repair of isolated problem
²verification of proper operation
2.0 IDENTIFICATION OF SYSTEM
The engine control module (ECM) is located in the center of the passenger compartment behind
the lower console. The sentry key immobilizer module is located below the steering column
behind the steering wheel.
3.0 SYSTEM DESCRIPTION AND FUNCTIONAL OPERATION
3.1 General Description
The 2.5L VM diesel engine system is equipped with the latest in technical advances. The
on-board diagnostics incorporated with the engine control module and SKIM are intended to
assist the field technician in repairing vehicle problems by the quickest means.
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3.2 Functional Operation
3.2.1 ECM On-Board Diagnostics
The ECM has been programmed to monitor many different circuits of the diesel fuel injection
system. This monitoring is called ``on-board diagnosis''.
Certain criteria must be met for a diagnostic trouble code to be entered into the ECM memory. The
criteria may be a range of: engine rpm, engine temperature, and/or input voltage to the ECM. If
all of the criteria for monitoring a system or circuit are met and a problem is sensed, then a trouble
code will be stored in the ECM.
It is possible that a trouble code for a monitored circuit may not be entered into the ECM memory
even though a malfunction has occurred. This may happen when the monitoring criteria have not
been met.
The ECM compares input signal voltages from each input device with specifications (the
established high and low limits of the range) that are programmed into it for that device. If the input
voltage is not within specifications and other trouble code criteria are met, a trouble code will be
stored in the ECM memory.
3.2.2 ECM Operating Modes
As input signals to the engine control module (ECM) change, the ECM adjusts its response to
output devices. For example, the ECM must calculate a different fuel quantity and fuel timing for
idle than it does for wide open throttle. There are several different modes of operation that
determine how the ECM responds to the various input signals.
Ignition Switch On (Engine Off Mode)
When the ignition switch activates the fuel injection system, the following actions occur:
1. The ECM determines atmospheric air pressure from the atmospheric pressure sensor
located in the ECM.
2. The ECM energizes the fuel quantity actuator and the fuel shudown solenoid if no faults
are present.
If the engine is not started within 5 seconds of ignition on, the ECM deactivates the fuel quantity
actuator and the fuel shutdown solenoid to prevent overheating.
Engine Start-Up Mode-The ECM uses the engine temperature sensor, fuel temperature sensor,
atmospheric pressure sensor, boost pressure sensor and the engine speed sensor to determine
fuel delivery during this mode.
Normal Driving Modes- Engine idle, warm-up, acceleration, deceleration and wide open throttle
modes are all controlled based on the sensor inputs to the ECM and are modified based on
engine temperature, boost pressure and engine speed.
Overheat Protection Mode- If engine temperature becomes too hot, the ECM activates high
speed radiator fan operation and limits fuel quantity for engine protection.
Limp-In Modes- The ECM operates in limp-in mode when certain system faults are detected.
The ECM operates in one of the following modes based on the severity of the fault:
1. 10% torque reduction.
2. 50% torque reduction.
3. Engine speed limited to 1100 rpm.
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After-Run- When fused ignition switch output is removed from the ECM cavity 47, the ECM
performs a self-diagnostic check in the following order:
1. Electrical shut-off test
2. Fuel quantity actuator test
3. Monitoring module test
4. Voltage regulator test
5. Main relay test (if tests 1-4 pass)
If any of tests 1-4 fail, the fault is stored in memory, and can be retrieved during the next ignition
cycle using the DRB.
3.2.3 Monitored Circuits
The ECM is able to monitor and identify most driveability related trouble conditions. Some circuits
are directly monitored through ECM feedback circuitry. In addition, the ECM monitors the voltage
state of some circuits and compares those states with expected values. Other systems are
monitored indirectly when the ECM conducts a rationality test to identify problems.
Although most subsystems of the powertrain control module are either directly or indirectly
monitored, there may be occasions when diagnostic trouble codes are not immediately identified.
For a trouble code to set, specific conditions must be met and unless these conditions are
encountered, a code will not set.
3.2.4 SKIS On-Board Diagnostics
The SKIS module has been programmed to transmit and monitor many different coded messages
as well as CCD Bus messages. This monitoring is called ``On-Board Diagnosis''.
Certain criteria must be met for a diagnostic trouble code to be entered into the Sentry Key
Immobilizer Module (SKIM) memory. The criteria may be a range of: input voltage, CCD Bus
messages, or coded messages to the SKIM. If all of the criteria for monitoring a circuit or function
are met and a fault is sensed, a diagnostic trouble code will be stored in the SKIM memory.
3.2.5 SKIS Overview
The Sentry Key Immobilizer System (SKIS) is an immobilizer system designed to prevent
unauthorized vehicle operation. The system consists of a Sentry Key Immobilizer Module (SKIM),
ignition key(s) equipped with a transponder chip, engine controller and body controller. When the
ignition switch is turned on, the SKIM interrogates the ignition key. If the ignition key is ªValidº the
SKIM sends a CCD Bus message to the body controller indicating the presence of a valid ignition
key. The BCM then supplies the ECM with a valid immobilizer signal allowing the engine to
continue to operate.
3.2.6 SKIS Operation
When ignition power is supplied to the SKIM, the SKIM performs an internal self-test. After the
self-test is completed, the SKIM energizes the antenna (this activates the transponder chip) and
sends a challenge to the transponder chip. The transponder chip responds to the challenge by
generating an encrypted response message using the following:
Secret Key þ This is an electronically stored value (identification number) that is unique to each
SKIS. The secret key is stored in the SKIM, BCM and all ignition key transponders.
Challenge þ This is a random number that is generated by the SKIM at each ignition key cycle.
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