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 Powertrain Control Mod-
ule (PCM). Use of an induction-type milliampere
ammeter, volt/ohmmeter, battery charger, carbon pile
rheostat (load tester), and 12-volt test lamp may be
required.

Certain starting system components are monitored

by the PCM 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 between 150 and 350 amperes (700
amperes - diesel engine), 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 portion of
the starter solenoid, and the starter motor. The low-
amperage control circuit components include the igni-
tion switch, the clutch pedal position switch (manual
transmission), the park/neutral position switch (auto-
matic transmission), the starter relay, the electro-
magnetic windings of the starter solenoid, and the
connecting wire harness components.

If the vehicle is equipped with a manual transmis-

sion, it has a clutch pedal position switch installed in
series between the ignition switch and the coil bat-
tery terminal of the starter relay. This normally open
switch prevents the starter relay from being ener-
gized when the ignition switch is turned to the
momentary Start position, unless the clutch pedal is
depressed. This feature prevents starter motor oper-
ation while the clutch disc and the flywheel are
engaged. The starter relay coil ground terminal is
always grounded on vehicles with a manual trans-
mission.

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/

STARTING

8F - 31

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
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
SYSTEM

The battery, starting system and charging system

in the vehicle operate with one another, and must be
tested as a complete system. In order for the engine
to start and the battery to charge properly, all of the
components that are used in these systems must per-
form within specifications. The service information
for these systems has been separated within this ser-
vice manual to make it easier to locate the specific
information

you

are

seeking.

However,

when

attempting to diagnose any of these systems, it is
important that you keep their interdependency in
mind.

The diagnostic procedures used for the battery,

starting system and charging system include the
most basic conventional diagnostic methods, to the
more sophisticated On-Board Diagnostics (OBD) built
into the Powertrain Control Module (PCM). Use of an
induction-type milliampere ammeter, a volt/ohmme-
ter, a battery charger, a carbon pile rheostat (load
tester) and a 12-volt test lamp may be required. All
OBD-sensed systems are monitored by the PCM.
Each monitored circuit is assigned a Diagnostic Trou-
ble Code (DTC). The PCM will store a DTC in elec-
tronic memory for any failure it detects. Refer to
Charging System, On-Board Diagnostic Test for
on-board diagnostic test procedures.

Starting System Diagnosis

Condition

Possible Cause

Correction

Starter fails to operate.

1. Battery discharged or
faulty.

1. Refer to 8, Battery. Replace faulty battery as required.

2. Starting circuit wiring
faulty.

2. Refer to Wiring. Test and repair faulty starter feed
and/or control circuits, as required.

3. Starter relay faulty.

3. Refer to Starter Relay. Replace faulty starter relay as
required.

4. Ignition switch faulty.

4. Refer to Ignition Switch and Key Lock Cylinder.
Replace faulty ignition switch as required.

5. Clutch pedal position
switch faulty.

5. Refer to Clutch Pedal Position Switch. Replace faulty
clutch hydraulic linkage unit as required.

6. Park/Neutral position
switch faulty or
misadjusted.

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

7. Starter solenoid faulty.

7. Refer to Starter Motors. Replace faulty starter motor as
required.

8F - 32

STARTING

STARTING (Continued)

Starting System Diagnosis

Condition

Possible Cause

Correction

8. Starter motor faulty.

8. Refer to Starter Motor. Replace faulty starter motor as
required.

Starter engages, fails to
turn engine.

1. Battery discharged or
faulty.

1. Refer to Battery. Replace faulty battery as required.

2. Starting circuit wiring
faulty.

2. Refer to Wiring. Test and repair faulty starter feed
and/or control circuits as required.

3. Starter motor faulty.

3. Refer to Starter Motor. Replace faulty starter motor as
required.

4. Engine seized.

4. Refer to 9, Engine Diagnosis. Repair or replace faulty
engine as required.

Starter engages, spins
out before engine starts.

1. Starter ring gear faulty.

1. Refer to Starter Motor. Remove starter motor to inspect
starter ring gear. Replace faulty starter ring gear as
required.

2. Starter motor faulty.

2. Refer to Starter Motor. Replace faulty starter motor as
required.

Starter does not
disengage.

1. Starter motor
improperly installed.

1. Refer to Starter Motor. Tighten starter motor mounting
hardware to correct tightness specifications as required.

2. Starter relay faulty.

2. Refer to Starter Relay. Replace faulty starter relay as
required.

3. Ignition switch faulty.

3. Refer to Ignition Switch and Key Lock Cylinder.
Replace faulty ignition switch as required.

4. Starter motor faulty.

4. Refer to Starter Motor. Replace faulty starter motor as
required.

TESTING

Before testing the starting system perform a visual

inspection of the starting system components and
connections.

COLD CRANKING TEST

Refer to Starting System in the index of this ser-

vice manual for the location of complete starting sys-
tem wiring diagrams. Before performing this test, be
certain that the following procedures are accom-
plished:

• The battery is fully-charged and load tested.

Refer to Battery Charging for battery charging pro-
cedures. Refer to Battery for battery diagnosis and
testing procedures, including battery load test proce-
dures.

• Fully engage the parking brake.

• If the vehicle is equipped with an automatic

transmission, place the gearshift selector lever in the
Park position. If the vehicle is equipped with a man-
ual transmission, place the gearshift selector lever in
the Neutral position and block the clutch pedal in the
fully depressed 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. See the fuse and relay lay-
out label affixed to the underside of the PDC cover
for ASD relay identification and location.

(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) 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 for starter motor diagnosis and
testing procedures. If the starter motor tests OK,
refer to Engine Diagnosis engine diagnosis and
testing procedures. If the starter motor is not OK,
replace faulty starter motor.

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

current (amperage) draw reads below specifica-
tions, refer to the Feed Circuit Testin this sec-
tion.

STARTING

8F - 33

STARTING (Continued)

the starter motor does not turn, refer to the Con-
trol Circuit Test in this section.

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

the starter motor turns very slowly, refer to the
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 starter feed circuit.

When performing the voltage drop test, it is impor-

tant to remember that the voltage drop is giving an
indication 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 terminal clamp and to the bat-
tery positive cable eyelet terminal at the starter sole-
noid B(+) terminal stud. If you probe the battery
positive terminal post and the battery positive cable
eyelet terminal at the starter solenoid B(+) terminal
stud, you are reading the combined voltage drop in
the battery positive cable terminal clamp-to-terminal
post connection and the battery positive cable.

The following operation will require a voltmeter

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

• The battery is fully-charged and load tested.

Refer to Battery Charging for battery charging pro-
cedures. Refer to Battery for battery diagnosis and

testing procedures, including battery load test proce-
dures.

• Fully engage the parking brake.

• If the vehicle is equipped with an automatic

• Verify that all lamps and accessories are turned

off.

• To prevent the engine from starting, remove the

(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 terminal clamp (Fig. 2). Rotate and hold the
ignition switch in the Start position. Observe the
voltmeter. If voltage is detected, correct the poor con-
tact between the battery negative cable terminal
clamp and the battery negative 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
terminal clamp (Fig. 3). Rotate and hold the ignition
switch in the Start position. Observe the voltmeter. If
voltage is detected, correct the poor connection
between the battery positive cable terminal clamp
and the battery positive terminal post.

Fig. 1 Volts-Amps Tester Connections - Typical

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

Fig. 2 Test Battery Negative Connection Resistance

- Typical

1 - VOLTMETER
2 - BATTERY

8F - 34

STARTING

STARTING (Continued)

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