Jeep Grand Cherokee WJ. Manual - part 612

Always begin by reading the diagnostic trouble

codes using the DRBIII

t. This will direct you to the

specific test(s) that must be performed.

3.3.1

HARD CODE

A diagnostic trouble code that comes back within

one cycle of the ignition key is a “hard” code. This
means that the fault is there every time the power-
train control module/engine control module/sentry
key immobilizer system checks that circuit or func-
tion. Procedures in this manual verify if the trouble
code is a hard code at the beginning of each test.
When it is not a hard code, an “intermittent” test
must be performed.

3.3.2

INTERMITTENT CODE

A diagnostic trouble code that is not there every

time the powertrain control module/engine control
module/sentry key immobilizer system checks the
circuit is an “intermittent” code. Most intermittent
codes are caused by wiring or connector problems.
Faults that come and go like this are the most
difficult to diagnose; they must be looked for under
specific conditions that cause them. The following
checks may assist you in identifying a possible
intermittent problem:

•

Visually inspect related wire harness connectors.
Look for broken, bent, pushed out, or corroded
terminals.

•

Visually inspect the related harnesses. Look for
chafed, pierced, or partially broken wire.

•

Refer to any hotlines or technical service bulle-
tins that may apply.

NOTE: Electro-magnetic (Radio) interference can

cause intermittent system malfunctions.

3.3.3

ECM DIAGNOSTIC TROUBLE CODES

A/C Control Open Circuit
A/C Control Short Circuit
Accelerator Pedal Sensor PWG Plausibility With

Potentiometer

Accelerator Pedal Sensor Supply High Exceeded
Accelerator Pedal Sensor Supply Low Exceeded
Accelerator Pedal Sensor Plausibility
Accelerator Pedal Sensor Signal High Exceeded
Atmosphere Pressure Sensor SRC High Exceeded
Atmosphere Pressure Sensor SRC Low Exceeded
Battery Voltage SRC High Exceeded
Brake Signal Plausibility With Redundant Con-

tact

Control Sleeve Sensor Signal Low Exceeded
Control Sleeve Sensor Start End Position Not

Attained

Control Sleeve Sensor Stop End Position Not

Attained

Turbocharger Boost Sensor Signal High Exceeded

Turbocharger Boost Sensor Signal Low Exceeded
Turbocharger Boost Sensor Supply High Ex-

ceeded

Turbocharger Boost Sensor Supply Low Exceeded
Turbocharger Boost Sensor Plausibility
EEPROM Plausibility Checksum Error in CC212
EEPROM Plausibility Checksum Error For Adj.

(EGR)

EEPROM Plausibility VIN Checksum Error
EEPROM Plausibility Communication With EE-

PROM

EEPROM Plausibility Ver Number Not Corre-

sponding

EEPROM Plausibility Func Switch Wrong or

Missing

EGR Open Circuit
EGR Short Circuit
Engine Speed Sensor Dynamic Plausibility
Engine Speed Sensor Overspeed Recognition
Engine Speed Sensor Static Plausibility
Fuel Quantity Actuator Negative Governor Devi-

ation Cold

Fuel Quantity Actuator Negative Governor Devi-

ation Warm

Fuel Quantity Actuator Positive Governor Devia-

tion Cold

Fuel Quantity Actuator Positive Governor Devia-

tion Warm

Fuel Temperature Sensor SRC High Exceeded
Fuel Temperature Sensor SRC Low Exceeded
Glow Relay #1 Controller Open Circuit
Glow Relay #2 Controller Open Circuit
Glow Relay #1 Controller Short Circuit
Glow Relay #2 Controller Short Circuit
Inductive Auxiliary Speed Sensor Dynamic Plau-

sibility

Inductive Auxiliary Speed Sensor Overspeed Rec-

ognition

Inductive Auxiliary Speed Sensor Plausibility
Inductive Auxiliary Speed Sensor Static Plausi-

bility

Air Temperature Sensor SRC High Exceeded
Air Temperature Sensor SRC Low Exceeded
Microcontroller Recovery Has Occurred
Microcontroller Prepare Fuel Quantity Stop
Microcontroller Redundant Overrun Monitoring
Microcontroller Gate-Array Monitoring
Microcontroller Gate-Array Watchdog
Needle Movement Sensor SRC High Exceeded
Needle Movement Sensor SRC Low Exceeded
Redundant Emergency Stop Plausibility In After-

Run

Redundant Emergency Stop Powerstage Defec-

tive

Regulator Lower Regulator Limit
Regulator Upper Regulator Limit
Solenoid Valve Controller Open Circuit
Solenoid Valve Controller Short Circuit

GENERAL INFORMATION

Temperature Of Engine Coolant SRC High Ex-

ceeded

Temperature Of Engine Coolant SRC Low Ex-

ceeded

Terminal 15 Plausibility After Start-Up
Timing Governor Negative Governor Deviation
Timing Governor Positive Governor Deviation
U-REF (2.5V)
Vehicle Speed Sensor PEC Frequency Too High
Vehicle Speed Sensor SRC High Exceeded
Vehicle Speed Sensor SRC Low Exceeded
Vehicle Theft Alarm Immobilizer Signal Lost
Vehicle Theft Alarm Invalid SKIM Message

3.3.4

PCM DIAGNOSTIC TROUBLE CODES

Amb/Batt Temperature Sensor Hi
Amb/Batt Temperature Sensor Low
Charging System Voltage Too High
Charging System Voltage Too Low
ECT Sensor Voltage Too High
ECT Sensor Voltage Too Low
Fuel Level Unit No Change Over Miles
Fuel Level Sending Unit Volts Too High
Fuel Level Sending Unit Volts Too Low
Generator Field Not Switching Properly
Internal Self-Test
Radiator Fan Control Relay Circuit
No Cluster Bus Message
Oil Pressure Voltage Too High
Oil Pressure Voltage Too Low
EEPROM Write Denied
No SKIM Bus Message Received
Wrong or Invalid Key Msg Received From SKIM
Speed Control Solenoid Circuits
Speed Control Power Relay or S/C 12v Driver

Circuit

PCM Failure SPI Communications
Speed Control Switch Always High
Speed Control Switch Always Low
Throttle Position Sensor Voltage Low
Throttle Position Sensor Voltage High
Trans 3-4 Shift Solenoid/Trans Relay Circuit
O/D Switch Pressed (Lo) More Than 5 Minutes
Low Output Speed Sensor RPM Above 15 MPH
Governor Pressure Above 3 PSI In Gear With 0

MPH

Governor Pressure Not Equal To Target @ 15-20

PSI

Governor Pressure Sensor Volts Too Low
Governor Pressure Sensor Volts Too Hi
Governor Pressure Sensor Offset Volts Too Low or

High

Governor Pressure Solenoid/Trans Relay Circuits
Trans Temperature Sensor Voltage Too Low
Trans Temperature Sensor Voltage Too High
Trans 12 Volt Supply Relay Control Circuit
Torque Converter Clutch Solenoid/Trans Relay

Circuit

3.3.5

SKIM DIAGNOSTIC TROUBLE CODES

ANTENNA FAILURE
COP FAILURE
EEPROM FAILURE
PCM STATUS FAILURE
INTERNAL FAULT
RAM FAILURE
ROLLING CODE FAILURE
SERIAL LINK EXTERNAL FAULT
SERIAL LINK INTERNAL FAULT
STACK OVERFLOW FAILURE
TRANSPONDER COMMUNICATION FAILURE
TRANSPONDER

CRC

(CYCLIC

REDUN-

DANCY CHECK) FAILURE

TRANSPONDER ID MISMATCH
TRANSPONDER RESPONSE MISMATCH
VIN MISMATCH

3.3.6

HANDLING NO TROUBLE CODE
PROBLEMS

After reading Section 3.0 (System Description

and Functional Operation), you should have a bet-
ter understanding of the theory and operation of the
on-board diagnostics, and how this relates to the
diagnosis of a vehicle that may have a driveability-
related symptom or complaint.

3.4

USING THE DRBIII

Refer to the DRBIII

t user’s guide for instructions

and assistance with reading trouble codes, erasing
trouble codes, and other DRBIII

t functions.

3.5

DRBIII

T ERROR MESSAGES AND

BLANK SCREEN

Under normal operation, the DRBIII

t will dis-

play one of only two error messages:

– User-Requested

WARM

Boot

User-

Requested COLD Boot

This is a sample of such an error message display:

ver: 2.14
date: 26 Jul93
file: key_itf.cc
date: Jul 26 1993
line: 548
err: 0x1
User-Requested COLD Boot

Press MORE to switch between this display

and the application screen.

Press F4 when done noting information.

3.5.1

DRBIII

T DOES NOT POWER UP

If the LEDs do not light or no sound is emitted at

start up, check for loose cable connections or a bad

GENERAL INFORMATION

cable. Check the vehicle battery voltage (data link
connector cavity 16). A minimum of 11 volts at DLC
cavity 16 is required to adequately power the
DRBIII

t. Check for proper ground connection at

DLC cavities 4 and 5.

If all connections are proper between the

DRBIII

t and the vehicle or other devices, and the

vehicle battery is fully charged, an inoperative
DRBIII

t may be the result of a faulty cable or

vehicle wiring. For a blank screen, refer to the
appropriate body diagnostic procedures manual.

3.5.2

DISPLAY IN NOT VISIBLE

Low temperatures will affect the visibility of the

display. Adjust the contrast to compensate for this
condition.

4.0

DISCLAIMERS, SAFETY,
WARNINGS

4.1

DISCLAIMERS

All information, illustrations, and specifications

contained in this manual are based on the latest
information available at the time of publication.
The right is reserved to make changes at any time
without notice.

4.2

SAFETY

4.2.1

TECHNICIAN SAFETY INFORMATION

WARNING: ENGINES PRODUCE CARBON
MONOXIDE THAT IS ODORLESS, CAUSES
SLOWER REACTION TIME, AND CAN LEAD
TO SERIOUS INJURY. WHEN THE ENGINE IS
OPERATING, KEEP SERVICE AREAS WELL
VENTILATED OR ATTACH THE VEHICLE
EXHAUST SYSTEM TO THE SHOP EXHAUST
REMOVAL SYSTEM.

Set the parking brake and block the wheels before

testing or repairing the vehicle. It is especially
important to block the wheels on front-wheel drive
vehicles; the parking brake does not hold the drive
wheels.

When servicing a vehicle, always wear eye pro-

tection, and remove any metal jewelry such as
watchbands or bracelets that might make an inad-
vertant electrical contact.

When diagnosing a powertrain system problem,

it is important to follow approved procedures where
applicable. These procedures can be found in the
service manual procedures. Following these proce-
dures is very important to the safety of individuals
performing diagnostic tests.

4.2.2

VEHICLE PREPARATION FOR
TESTING

Make sure the vehicle being tested has a fully

charged battery. If it does not, false diagnostic codes
or error messages may occur.

4.2.3

SERVICING SUB-ASSEMBLIES

Some components of the powertrain system are

intended to be serviced in assembly only. Attempt-
ing to remove or repair certain system sub-
components may result in personal injury and/or
improper system operation. Only those components
with approved repair and installation procedures in
the service manual should be serviced.

4.2.4

DRBIII

T SAFETY INFORMATION

WARNING: EXCEEDING THE LIMITS OF THE
DRBIII

MULTIMETER IS DANGEROUS. IT

CAN

EXPOSE

YOU

SERIOUS

POSSIBLY

FATAL

INJURY.

CAREFULLY

READ AND UNDERSTAND THE CAUTIONS
AND THE SPECIFICATION LIMITS.

Follow the vehicle manufacturer’s service specifi-

cations at all times.

•

Do not use the DRBIII

t if it has been damaged.

GENERAL INFORMATION

•

Do not use the test leads if the insulation is
damaged or if metal is exposed.

•

To avoid electrical shock, do not touch the test
leads, tips, or the circuit being tested.

•

Choose the proper range and function for the
measurement. Do not try voltage or current mea-
surements that may exceed the rated capacity.

•

Do not exceed the limits shown in the table below:

FUNCTION

INPUT LIMIT

Volts

0 - 500 peak volts AC
0 - 500 volts DC

Ohms (resistance)*

0 - 1.12 megohms

Frequency Measured
Frequency Generated

0 - 10 kHz

Temperature

-58 - 1100°F
-50 - 600°C

* Ohms cannot be measured if voltage is present.

Ohms can be measured only in a non-powered
circuit.

•

Voltage between any terminal and ground must
not exceed 500v DC or 500v peak AC.

•

Use caution when measuring voltage above 25v
DC or 25v AC.

•

The circuit being tested must be protected by a
10A fuse or circuit breaker.

•

Use the low current shunt to measure circuits up
to 10A. Use the high current clamp to measure
circuits exceeding 10A.

•

When testing for the presence of voltage or cur-
rent, make sure the meter is functioning cor-
rectly. Take a reading of a known voltage or
current before accepting a zero reading.

•

When measuring current, connect the meter in
series with the load.

•

Disconnect the live test lead before disconnecting
the common test lead.

4.3

WARNINGS

4.3.1

VEHICLE DAMAGE WARNINGS

Before disconnecting any control module, make

sure the ignition is “off”. Failure to do so could
damage the module.

When testing voltage or continuity at any control

module, use the terminal side (not the wire end) of
the connector. Do not probe a wire through the
insulation; this will damage it and eventually cause
it to fail because of corrosion.

Be careful when performing electrical tests so as

to prevent accidental shorting of terminals. Such
mistakes can damage fuses or components. Also, a

second code could be set, making diagnosis of the
original problem more difficult.

4.3.2

ROAD TESTING A COMPLAINT
VEHICLE

Some complaints will require a test drive as part

of the repair verification procedure. The purpose of
the test drive is to try to duplicate the diagnostic
code or symptom condition.

CAUTION:

BEFORE

ROAD

TESTING

VEHICLE,

SURE

THAT

ALL

COMPONENTS

ARE

REASSEMBLED.

DURING THE TEST DRIVE, DO NOT TRY TO
READ

THE

DRBIII

SCREEN

WHILE

MOTION. DO NOT HANG THE DRBIII

FROM

THE REAR VIEW MIRROR OR OPERATE IT
YOURSELF.

HAVE

ASSISTANT

AVAILABLE TO OPERATE THE DRBIII

5.0

REQUIRED TOOLS AND
EQUIPMENT

ammeter
DRBIII

t (diagnostic read-out box) scan tool

glow plug test kit
jumper wires and probes
ohmmeter
vacuum gauge
voltmeter

6.0

GLOSSARY OF TERMS

backfire,
popback

fuel ignites in either the intake or
the exhaust system

BCM

body control module

cuts out,
misses

a steady pulsation or the inability of
the engine to maintain a consistent
rpm

DLC

data link connector (previously
called “engine diagnostic connector”)

detona-
tion, pre-
ignition

a mild to severe ping, especially un-
der loaded engine conditions

ECM

engine control module

ECT

engine coolant temperature sensor

EGR

exhaust gas recirculation valve and
system

genera-
tor

previously called “alternator”

GENERAL INFORMATION

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