Jeep Grand Cherokee WJ. Manual - part 89

Starting System Diagnosis

CONDITION

POSSIBLE CAUSE

CORRECTION

STARTER FAILS TO
OPERATE.

1. Battery discharged or
faulty.
2. Starting circuit wiring
faulty.
3. Starter relay faulty.
4. Ignition switch faulty.
5. Park/Neutral position
switch faulty or
misadjusted.
6. Starter solenoid faulty.
7. Starter motor faulty.

1. Refer to Battery in the Diagnosis and Testing section of
Group 8A - Battery. Charge or replace the battery, if
required.
2. Refer to Starting System in Group 8W - Wiring
Diagrams. Test and repair the starter feed and/or control
circuits, if required.
3. Refer to Starter Relay in the Diagnosis and Testing
section of this group. Replace the starter relay, if
required.
4. Refer to Ignition Switch and Key Lock Cylinder in the
Diagnosis and Testing section of Group 8D - Ignition
System. Replace the ignition switch, if required.
5. Refer to Park/Neutral Position Switch in the Diagnosis
and Testing section of Group 21 - Transmission. Replace
the park/neutral position switch, if required.
6. Refer to Starter Motor in the Diagnosis and Testing
section of this group. Replace the starter motor assembly,
if required.
7. If all other starting system components and circuits test
OK, replace the starter motor assembly.

STARTER ENGAGES,
FAILS TO TURN
ENGINE.

1. Battery discharged or
faulty.
2. Starting circuit wiring
faulty.
3. Starter motor faulty.
4. Engine seized.

STARTER ENGAGES,
SPINS OUT BEFORE
ENGINE STARTS.

1. Starter ring gear faulty.
2. Starter motor faulty.

1. Refer to Starter Motor in the Removal and Installation
section of this group. Remove the starter motor to inspect
the starter ring gear. Replace the starter ring gear, if
required.
2. If all other starting system components and circuits test
OK, replace the starter motor assembly.

STARTER DOES NOT
DISENGAGE.

1. Starter motor
improperly installed.
2. Starter relay faulty.
3. Ignition switch faulty.
4. Starter motor faulty.

1. Refer to Starter Motor in the Removal and Installation
section of this group. Tighten the starter mounting
hardware to the correct tightness specifications.
2. Refer to Starter Relay in the Diagnosis and Testing
section of this group. Replace the starter relay, if
required.
3. Refer to Ignition Switch and Key Lock Cylinder in the
Diagnosis and Testing section of Group 8D - Ignition
System. Replace the ignition switch, if required.
4. If all other starting system components and circuits test
OK, replace the starter motor assembly.

8B - 4

STARTING SYSTEMS

DIAGNOSIS AND TESTING (Continued)

INSPECTION

For complete circuit diagrams, refer to Starting

System in the Contents of Group 8W - Wiring Dia-
grams. Before removing any unit from the starting
system for repair or diagnosis, perform the following
inspections:

WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS,

REFER

GROUP

PASSIVE

RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING

WHEEL,

STEERING

COLUMN,

INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.

• Battery - Visually inspect the battery for indi-

cations of physical damage and loose or corroded
cable connections. Determine the state-of-charge and
cranking capacity of the battery. Charge or replace
the battery, if required. Refer to Battery in the
proper section of Group 8A - Battery for complete ser-
vice information for the battery.

• Ignition Switch - Visually inspect the ignition

switch for indications of physical damage and loose
or corroded wire harness connections. Refer to Igni-
tion Switch and Key Lock Cylinder in the proper
section of Group 8D - Ignition System for complete
service information for the ignition switch.

•

Park/Neutral Position Switch - Visually

inspect the park/neutral position switch for indica-
tions of physical damage and loose or corroded wire
harness connections. Refer to Park/Neutral Posi-
tion Switch in the proper section of Group 21 -
Transmission for complete service information for the
park/neutral position switch.

• Starter Relay - Visually inspect the starter

relay for indications of physical damage and loose or
corroded wire harness connections.

• Starter Motor - Visually inspect the starter

motor for indications of physical damage and loose or
corroded wire harness connections.

• Starter Solenoid - Visually inspect the starter

solenoid for indications of physical damage and loose
or corroded wire harness connections.

• Wiring - Visually inspect the wire harnesses for

damage. Repair or replace any faulty wiring, as
required. Refer to the proper section of Group 8W -
Wiring Diagrams for complete service information
and circuit diagrams for the starting system wiring
components.

TESTING

COLD CRANKING TEST

For complete circuit diagrams, refer to Starting

System in the Contents of Group 8W - Wiring Dia-
grams. The battery must be fully-charged and load-
tested before proceeding. Refer to Battery in the
Diagnosis and Testing section of Group 8A - Battery
for the procedures.

(1) Connect a suitable volt-ampere tester to the

battery terminals (Fig. 1). See the instructions pro-
vided by the manufacturer of the volt-ampere tester
being used.

(2) Fully engage the parking brake.
(3) Place the automatic transmission gearshift

selector lever in the Park position.

(4) Verify that all lamps and accessories are

turned off.

(5) To prevent the engine from starting, remove

the Automatic ShutDown (ASD) relay. The ASD relay
is located in the Power Distribution Center (PDC), in
the engine compartment. Refer to the fuse and relay
layout label affixed to the underside of the PDC cover
for ASD relay identification and location.

(6) Rotate and hold the ignition switch in the Start

position. Note the cranking voltage and current
(amperage) draw readings shown on the volt-ampere
tester.

(a) If the voltage reads below 9.6 volts, refer to

Starter Motor in the Diagnosis and Testing sec-
tion of this group. If the starter motor is OK, refer
to Engine Diagnosis in the Diagnosis and Testing
section of Group 9 - Engine for further testing of
the engine. If the starter motor is not OK, replace
the faulty starter motor.

Fig. 1 Volts-Amps Tester Connections - Typical

1 – POSITIVE CLAMP
2 – NEGATIVE CLAMP
3 – INDUCTION AMMETER CLAMP

STARTING SYSTEMS

8B - 5

DIAGNOSIS AND TESTING (Continued)

(b) If the voltage reads above 9.6 volts and the

current (amperage) draw reads below specifica-
tions, refer to Feed Circuit Test in this section.

the starter motor does not turn, refer to Control
Circuit Testing in this section.

(d) If the voltage reads 12.5 volts or greater and

the starter motor turns very slowly, refer to Feed
Circuit Test in this section.

NOTE: A cold engine will increase the starter cur-
rent (amperage) draw reading, and reduce the bat-
tery voltage reading.

FEED CIRCUIT TEST

The starter feed circuit test (voltage drop method)

will determine if there is excessive resistance in the
high-amperage feed circuit. For complete circuit dia-
grams, refer to Starting System in the Contents of
Group 8W - Wiring Diagrams.

When performing these tests, it is important to

remember that the voltage drop is giving an indica-
tion of the resistance between the two points at
which the voltmeter probes are attached.

Example: When testing the resistance of the bat-

tery positive cable, touch the voltmeter leads to the
battery positive cable clamp and the cable connector
at the starter solenoid. If you probe the battery pos-
itive terminal post and the cable connector at the
starter solenoid, you are reading the combined volt-
age drop in the battery positive cable clamp-to-termi-
nal post connection and the battery positive cable.

The following operation will require a voltmeter

accurate to 1/10 (0.10) volt. Before performing the
tests, be certain that the following procedures are
accomplished:

• Battery is fully-charged and load-tested. Refer to

Battery in the Diagnosis and Testing section of
Group 8A - Battery for the procedures.

• Fully engage the parking brake.

• Place the automatic transmission gearshift selec-

tor lever in the Park position.

• Verify that all lamps and accessories are turned

off.

• To prevent the engine from starting, remove the

Automatic ShutDown (ASD) relay. The ASD relay is
located in the Power Distribution Center (PDC), in
the engine compartment. Refer to the fuse and relay
layout label affixed to the underside of the PDC cover
for ASD relay identification and location.

(1) Connect the positive lead of the voltmeter to

the battery negative terminal post. Connect the neg-
ative lead of the voltmeter to the battery negative
cable clamp (Fig. 2). Rotate and hold the ignition
switch in the Start position. Observe the voltmeter. If

voltage is detected, correct the poor contact between
the cable clamp and the terminal post.

(2) Connect the positive lead of the voltmeter to

the battery positive terminal post. Connect the nega-
tive lead of the voltmeter to the battery positive cable
clamp (Fig. 3). Rotate and hold the ignition switch in
the Start position. Observe the voltmeter. If voltage
is detected, correct the poor contact between the
cable clamp and the terminal post.

(3) Connect the voltmeter to measure between the

battery positive terminal post and the starter sole-
noid battery terminal stud (Fig. 4). Rotate and hold
the ignition switch in the Start position. Observe the
voltmeter. If the reading is above 0.2 volt, clean and

Fig. 2 Test Battery Negative Connection Resistance

- Typical

1 – VOLTMETER
2 – BATTERY

Fig. 3 Test Battery Positive Connection Resistance -

Typical

1 – VOLTMETER
2 – BATTERY

8B - 6

STARTING SYSTEMS

DIAGNOSIS AND TESTING (Continued)

tighten the battery cable connection at the solenoid.
Repeat the test. If the reading is still above 0.2 volt,
replace the faulty battery positive cable.

(4) Connect the voltmeter to measure between the

battery negative terminal post and a good clean
ground on the engine block (Fig. 5). Rotate and hold
the ignition switch in the Start position. Observe the
voltmeter. If the reading is above 0.2 volt, clean and
tighten the battery negative cable attachment on the
engine block. Repeat the test. If the reading is still
above 0.2 volt, replace the faulty battery negative
cable.

(5) Connect the positive lead of the voltmeter to

the starter housing. Connect the negative lead of the

voltmeter to the battery negative terminal post (Fig.
6). Rotate and hold the ignition switch in the Start
position. Observe the voltmeter. If the reading is
above 0.2 volt, correct the poor starter to engine
block ground contact.

If the resistance tests detect no feed circuit prob-

lems, refer to Starter Motor in the Diagnosis and
Testing section of this group.

CONTROL CIRCUIT TESTING

The starter control circuit components should be

tested in the order in which they are listed, as fol-
lows:

• Starter Relay - Refer to Starter Relay in the

Diagnosis and Testing section of this group for the
procedures.

• Starter Solenoid - Refer to Starter Motor in

the Diagnosis and Testing section of this group for
the procedures.

• Ignition Switch - Refer to Ignition Switch

and Key Lock Cylinder in the Diagnosis and Test-
ing section of Group 8D - Ignition System for the pro-
cedures.

•

Park/Neutral Position Switch - Refer to

Park/Neutral Position Switch in the Diagnosis
and Testing section of Group 21 - Transmission for
the procedures.

• Wire harnesses and connections - Refer to

Starting System in the Contents of Group 8W -
Wiring Diagrams for complete circuit diagrams.

STARTER MOTOR

Correct starter motor operation can be confirmed

by performing the following free running bench test.
This test can only be performed with the starter
motor removed from the vehicle. Refer to Starting

Fig. 4 Test Battery Positive Cable Resistance -

Typical

1 – BATTERY
2 – VOLTMETER
3 – STARTER MOTOR

Fig. 5 Test Ground Circuit Resistance - Typical

1 – VOLTMETER
2 – BATTERY
3 – ENGINE GROUND

Fig. 6 Test Starter Ground - Typical

1 – STARTER MOTOR
2 – BATTERY
3 – VOLTMETER

STARTING SYSTEMS

8B - 7

DIAGNOSIS AND TESTING (Continued)

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