Hummer H3. Manual — part 43

Relay Replacement (Attached to Wire Harness) or Relay Replacement (Within an
Electrical Center)

Starter Motor Replacement (LH8) or Starter Motor Replacement (LLR)

Control Module References for ECM replacement, setup, and programming

STARTER SOLENOID CLICKS, ENGINE DOES NOT CRANK

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

When the ignition switch is placed in the START position, a discrete signal is supplied to the
body control module (BCM) notifying it that the ignition is in the START position. The BCM
then sends a message to the engine control module (ECM) that crank has been requested. The
ECM then verifies that the transmission is in Park or Neutral. If it is, the ECM then supplies 12
volts to the control circuit of the STRTR relay. When this occurs, battery voltage is supplied
through the switch of the STRTR relay to S terminal of the starter solenoid.

Reference Information

Schematic Reference

Starting and Charging Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Starting System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

2008 Hummer H3

2008 ENGINE Engine Electrical - H3

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Verify that battery is sufficiently charged and that the battery cables are clean and tight.

If battery not sufficiently charged, refer to Battery Charging.

If battery cables are not within specified range, refer to Fastener Tightening
Specifications.

2. Turn the ignition switch to the start position. The starter solenoid should click.

If starter solenoid does not click, refer to Starter Solenoid Does Not Click
(Automatic M30) or Starter Solenoid Does Not Click (Manual MA5).

3. Remove the drive belt. Refer to Drive Belt Replacement (Without A/C) or Drive Belt

Replacement (With A/C) for the 3.7L engine, or Drive Belt Replacement - Accessory
for the 5.3L engine.

4. Turn the ignition switch to the START position.

If the engine cranks, inspect the engine and belt drive system for mechanical binding,
seized engine, or seized generator, etc.

If the engine does not crank, refer to Engine Will Not Crank - Crankshaft Will Not
Rotate for the 3.7L engine, or Engine Will Not Crank - Crankshaft Will Not
Rotate for the 5.3L engine.

5. Using a DMM, measure between the positive battery cable and terminal B at the solenoid as

the ignition switch is turned to the START position. Voltage should be less than 0.5 volt.

If greater than the specified value, replace the positive battery cable.

6. Using a DMM, measure the negative battery cable to the starter motor case as the ignition

switch is turned to the START position. Voltage should be less than 0.5 volt.

If greater than the specified value, replace the negative battery cable.

7. If all circuits test normal, replace the starter motor.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

2008 Hummer H3

2008 ENGINE Engine Electrical - H3

Battery Positive and Negative Cable Replacement (LLR)

Starter Motor Replacement (LH8) or Starter Motor Replacement (LLR)

ENGINE CRANKS SLOWLY

Inspect the following items:

Battery-Perform the Battery Inspection/Test. Refer to Battery Inspection/Test.

Wiring-Inspect the wiring for damage. Inspect all connections to the starter motor, the
solenoid, the battery, and all ground connections. Refer to:

Circuit Testing

Wiring Repairs

Testing for Intermittent Conditions and Poor Connections

Connector Repairs

Engine-Verify that the engine is not seized.

If the battery, the wiring, and the engine are functioning properly, and the engine continues to
crank slowly, replace the starter motor. Refer to Starter Motor Replacement (LH8) or Starter
Motor Replacement (LLR).

STARTER MOTOR NOISE DIAGNOSIS

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Testing

1. Remove the flywheel inspection cover.

2. Inspect the flywheel for the following:

Loose flywheel bolts

Chipped gear teeth

Missing gear teeth

Bent flywheel

If not within specifications, secure the flywheel bolts or replace the flywheel.

2008 Hummer H3

2008 ENGINE Engine Electrical - H3

If all inspections were within specification, replace the starter motor.

Repair Procedures

Fastener Tightening Specifications for the 3.7L engine or Fastener Tightening
Specifications for the 5.3L engine

Engine Flywheel Replacement (with Automatic Transmission) or Engine Flywheel
Replacement (with Manual Transmission) for the 3.7L engine or Automatic
Transmission Flex Plate Replacement for the 5.3L engine

Starter Motor Replacement (LH8) or Starter Motor Replacement (LLR)

REPAIR INSTRUCTIONS

BATTERY NEGATIVE CABLE DISCONNECTION AND CONNECTION

Disconnecting Procedure

CAUTION: Batteries produce explosive gases. Batteries contain

corrosive acid. Batteries supply levels of electrical current
high enough to cause burns. Therefore, in order to reduce the
risk of personal injury while working near a battery, observe
the following guidelines:

Always shield your eyes.

Avoid leaning over the battery whenever possible.

Do not expose the battery to open flames or sparks.

Do not allow battery acid to contact the eyes or the skin.

Flush any contacted areas with water immediately
and thoroughly.

Get medical help.

CAUTION: Unless directed otherwise, the ignition and start switch must

be in the OFF or LOCK position, and all electrical loads must
be OFF before servicing any electrical component. Disconnect
the negative battery cable to prevent an electrical spark
should a tool or equipment come in contact with an exposed
electrical terminal. Failure to follow these precautions may
result in personal injury and/or damage to the vehicle or its

2008 Hummer H3

2008 ENGINE Engine Electrical - H3