ate in conjunction with one another, and must be
tested as a complete system. For correct operation of
starting/charging systems, all components used in
these 3 systems must perform within specifications.
When attempting to diagnose any of these systems, it
is important that you keep their interdependency in
mind.

The diagnostic procedures used in each of these

groups include the most basic conventional diagnostic
methods, to the more sophisticated On-Board Diag-
nostics (OBD) built into the Engine Control Module
(ECM). Use of an induction-type milliampere amme-
ter, volt/ohmmeter, battery charger, carbon pile rheo-
stat (load tester), and 12-volt test lamp may be
required.

Certain starting system components are monitored

by the ECM and may produce a Diagnostic Trouble
Code (DTC).

OPERATION

The starting system components form two separate

circuits. A high-amperage feed circuit that feeds the
starter motor high-amperage, and a low-amperage

control circuit that operates on less than 20 amperes.
The high-amperage feed circuit components include
the battery, the battery cables, the contact disc por-
tion of the starter solenoid, and the starter motor
itself. The low-amperage control circuit components
include the ignition switch, the park/neutral position
switch (automatic transmission), the starter relay,
the electromagnetic windings of the starter solenoid,
and the connecting wire harness components.

If the vehicle is equipped with an automatic trans-

mission, battery voltage is supplied through the low-
amperage control circuit to the coil battery terminal
of the starter relay when the ignition switch is
turned to the momentary Start position. The park/
neutral position switch is installed in series between
the starter relay coil ground terminal and ground.
This normally open switch prevents the starter relay
from being energized and the starter motor from
operating unless the automatic transmission gear
selector is in the Neutral or Park positions.

When the starter relay coil is energized, the nor-

mally open relay contacts close. The relay contacts
connect the relay common feed terminal to the relay
normally open terminal. The closed relay contacts
energize the starter solenoid coil windings.

The energized solenoid pull-in coil pulls in the sole-

noid plunger. The solenoid plunger pulls the shift
lever in the starter motor. This engages the starter
overrunning clutch and pinion gear with the starter
ring gear on the manual transmission flywheel or on
the

automatic

transmission

torque

converter

torque converter drive plate.

As the solenoid plunger reaches the end of its

travel, the solenoid contact disc completes the high-
amperage starter feed circuit and energizes the sole-
noid plunger hold-in coil. Current now flows between
the solenoid battery terminal and the starter motor,
energizing the starter.

Once the engine starts, the overrunning clutch pro-

tects the starter motor from damage by allowing the

8F - 28

STARTING SYSTEM

starter pinion gear to spin faster than the pinion
shaft. When the driver releases the ignition switch to
the On position, the starter relay coil is de-energized.
This causes the relay contacts to open. When the
relay contacts open, the starter solenoid plunger
hold-in coil is de-energized.

When the solenoid plunger hold-in coil is de-ener-

gized, the solenoid plunger return spring returns the
plunger to its relaxed position. This causes the con-
tact disc to open the starter feed circuit, and the shift
lever to disengage the overrunning clutch and pinion
gear from the starter ring gear.

DIAGNOSIS AND TESTING - STARTING SYS-
TEM

The battery, starting, and charging systems oper-

ate in conjunction with one another, and must be
tested as a complete system. For correct starting/
charging system operation, all of the components
involved in these 3 systems must perform within
specifications.

Starting System Diagnosis

CONDITION

POSSIBLE CAUSE

CORRECTION

STARTER FAILS TO
OPERATE.

1. Battery discharged or
faulty.

1. Refer to Battery. Charge or replace battery, if re-
quired.

2. Starting circuit wiring
faulty.

2. Refer to 8, Wiring Diagrams. Test and repair starter
feed and/or control circuits, if required.

3. Starter relay faulty.

3. Refer to Starter Relay in Diagnosis and Testing. Re-
place starter relay if required.

4. Ignition switch faulty.

4. Refer to Ignition Switch and Key Lock Cylinder. Re-
place ignition switch if required.

5. Clutch pedal position
switch faulty.

5. Refer to Clutch Pedal Position Switch.

6. Park/Neutral position
switch faulty or misad-
justed.

6. Refer to Park/Neutral Position Switch. Replace park/
neutral position switch if required.

7. Starter solenoid faulty.

7. Refer to Starter Motor. Replace starter motor assem-
bly if required.

8. Starter motor faulty.

8. If all other starting system components and circuits
test OK, replace starter motor.

STARTER ENGAGES,
FAILS TO TURN EN-
GINE.

1. Battery discharged or
faulty.

1. Refer to Battery. Charge or replace battery if re-
quired.

2. Starting circuit wiring
faulty.

2. Refer to 8, Wiring Diagrams. Test and repair starter
feed and/or control circuits if required.

3. Starter motor faulty.

3. If all other starting system components and circuits
test OK, replace starter motor assembly.

4. Engine seized.

4. Refer to Engine Diagnosis in the Diagnosis and Test-
ing section of 9, Engine.

STARTER ENGAGES,
SPINS OUT BEFORE
ENGINE STARTS.

1. Starter ring gear
faulty.

1. Refer to Starter Motor Removal and Installation. Re-
move starter motor to inspect starter ring gear. Replace
starter ring gear if required.

2. Starter motor faulty.

2. If all other starting system components and circuits
test OK, replace starter motor assembly.

STARTING SYSTEM

8F - 29

Starting System Diagnosis

CONDITION

POSSIBLE CAUSE

CORRECTION

STARTER DOES NOT
DISENGAGE.

1. Starter motor improp-
erly installed.

1. Refer to Starter Motor Removal and Installation.
Tighten starter mounting hardware to correct torque
specifications.

2. Starter relay faulty.

2. Refer to Starter Relay Diagnosis and Testing. Re-
place starter relay if required.

3. Ignition switch faulty.

3. Refer to Ignition Switch and Key Lock Cylinder. Re-
place ignition switch if required.

4. Starter motor faulty.

4. If all other starting system components and circuits
test OK, replace starter motor.

INSPECTION

For complete starter wiring circuit diagrams, refer

to 8, Wiring Diagrams. Before removing any unit
from starting system for repair or diagnosis, perform
the following inspections:

WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO 8, PASSIVE RESTRAINT SYS-
TEMS,

BEFORE

ATTEMPTING

ANY

STEERING

WHEEL, STEERING COLUMN, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT AND POSSIBLE PERSONAL INJURY.

• Battery - Visually inspect battery for indica-

tions of physical damage and loose or corroded cable
connections. Determine state-of-charge and cranking
capacity of battery. Charge or replace battery if
required. Refer to Battery in 8, Battery.

• Ignition Switch - Visually inspect ignition

switch for indications of physical damage and loose
or corroded wire harness connections. Refer to Igni-
tion Switch and Key Lock Cylinder.

• Park/Neutral Position Switch - Visually

inspect park/neutral position switch for indications of
physical damage and loose or corroded wire harness
connections.

Refer

Park/Neutral

Position

Switch in 21, Transmission.

• Starter Relay - Visually inspect starter relay

for indications of physical damage and loose or cor-
roded wire harness connections.

• Starter Motor - Visually inspect starter motor

for indications of physical damage and loose or cor-
roded wire harness connections.

• Starter Solenoid - Visually inspect starter sole-

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

• Wiring - Visually inspect wire harnesses for

damage or corrosion. Repair or replace any faulty
wiring, as required. Refer to 8, Wiring Diagrams.

TESTING

COLD CRANKING TEST

For complete starter wiring circuit diagrams, refer

to 8, Wiring Diagrams. The battery must be fully-
charged and load-tested before proceeding. Refer to
Battery in 8, Battery.

(1) Connect volt-ampere tester to battery terminals

(Fig. 1). See instructions provided by manufacturer of
volt-ampere tester being used.

(2) Fully engage parking brake.
(3) Place gearshift selector lever in Park position.
(4) Verify that all lamps and accessories are

turned off.

(5) To prevent engine from starting, remove Fuel

Pump Relay. This relay is located in Power Distribu-
tion Center (PDC). Refer to label on PDC cover for
relay location.

WARNING: IF EQUIPPED WITH DIESEL ENGINE,
ATTEMPT

START

ENGINE

FEW

TIMES

BEFORE PROCEEDING WITH FOLLOWING STEP.

Fig. 1 VOLTS-AMPS TESTER CONNECTIONS -

TYPICAL

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

8F - 30

STARTING SYSTEM

(6) Rotate and hold ignition switch in Start posi-

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

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

Starter Motor in Diagnosis and Testing. If starter
motor is OK, refer to Engine Diagnosis in 9,
Engine for further testing of engine. If starter
motor is not OK, replace faulty starter motor.

(b) If voltage reads above 9.6 volts and current

(amperage) draw reads below specifications, refer
to Feed Circuit Test in this section.

starter motor does not turn, refer to Control Cir-
cuit Testing in this section.

(d) If voltage reads 12.5 volts or greater and

starter motor turns very slowly, refer to Feed Cir-
cuit Test in this section.

NOTE: A cold engine will increase starter current
(amperage) draw reading, and reduce battery volt-
age reading.

FEED CIRCUIT TEST

The starter feed circuit test (voltage drop method)

will determine if there is excessive resistance in
high-amperage feed circuit. For complete starter wir-
ing circuit diagrams, refer 8, Wiring Diagrams.

When performing these tests, it is important to

remember that voltage drop is giving an indication of
resistance between two points at which voltmeter
probes are attached.

Example: When testing resistance of positive bat-

tery cable, touch voltmeter leads to positive battery
cable clamp and cable connector at starter solenoid.
If you probe positive battery terminal post and cable
connector at starter solenoid, you are reading com-
bined voltage drop in positive battery cable clamp-to-
terminal post connection and positive battery cable.

The following operation will require a voltmeter

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

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

Battery in 8, Battery.

• Fully engage parking brake.

• Place gearshift selector lever in Park position.

• Verify that all lamps and accessories are turned

off.

• To prevent engine from starting, remove Fuel

Pump Relay. This relay is located in Power Distribu-
tion Center (PDC). Refer to label on PDC cover for
relay location.

(1) Connect positive lead of voltmeter to negative

battery cable terminal post. Connect negative lead of
voltmeter to negative battery cable clamp (Fig. 2).
Rotate and hold ignition switch in Start position.
Observe voltmeter. If voltage is detected, correct poor

contact between cable clamp and terminal post.

(2) Connect positive lead of voltmeter to positive

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

(3) Connect voltmeter to measure between battery

positive terminal post and starter solenoid battery
terminal stud (Fig. 4). Rotate and hold ignition
switch in Start position. Observe voltmeter. If read-
ing is above 0.2 volt, clean and tighten battery cable
connection at solenoid. Repeat test. If reading is still
above 0.2 volt, replace faulty positive battery cable.

Fig. 2 TEST NEGATIVE BATTERY CABLE

CONNECTION RESISTANCE - TYPICAL

1 - VOLTMETER
2 - BATTERY

Fig. 3 TEST POSITIVE BATTERY CABLE

CONNECTION RESISTANCE - TYPICAL

1 - VOLTMETER
2 - BATTERY

STARTING SYSTEM

8F - 31

Content .. 43 44 45 46 ..