Hummer H3. Manual — part 42

1. Ignition OFF, remove the relay.

2. Test for 60-180 ohms between terminals 85 and 86.

If not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

30 and 86

30 and 87

30 and 85

85 and 87

If not the specified value, replace the relay.

4. Install a 20A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper

wire between relay terminal 86 and ground. Test for less than 2.0 ohms between terminals
30 and 87.

If greater than specified range, replace the relay.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Range Selector Lever Cable Adjustment (3.7L) or Range Selector Lever Cable
Adjustment (5.3L)

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

Park/Neutral Position and Backup Lamp Switch Replacement (3.7L) or
Park/Neutral Position and Backup Lamp Switch Replacement (5.3L)

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

Control Module References for ECM replacement, setup, and programming

STARTER SOLENOID DOES NOT CLICK (MANUAL MA5)

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.

Diagnostic Fault Information

2008 Hummer H3

2008 ENGINE Engine Electrical - H3

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 clutch pedal is pressed. If it is, the ECM then supplies 12 volts to the
control circuit of the PCM CNTRL relay. When this occurs, battery voltage is supplied through
the switch of the PCM CNTRL relay to terminal A X1 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

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

B+

1

1

-

-

PCM-1 Ignition Voltage

1

1

-

-

Relay Control

1

1

2

-

Starter Control

1

1

2

-

Ground

-

1

-

-

1. No crank
2. Cranks all the time

2008 Hummer H3

2008 ENGINE Engine Electrical - H3

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, verify that the scan tool ECM Ignition 1 Signal parameter displays B+.

If less than the specified value, test the PCM-1 fuse, the RUN/CRNK relay, and the
ignition voltage circuit for an open/high resistance. If the circuit tests normal, replace
the ECM.

2. Verify that no starter relay, theft deterrent, or clutch pedal DTCs are set that would cause

the ECM to disable starting.

If DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

3. Ignition ON, observe the scan tool ECM Crank Request Signal parameter. Place ignition

switch in the crank position, the parameter should display Yes.

If not the specified value, refer to Power Mode Mismatch .

4. With the transmission in neutral and clutch pedal fully pressed, verify the scan tool ECM

Clutch Start Switch parameter displays Applied.

If the ECM Clutch Start Switch parameter does not indicate Applied, refer to Clutch
Pedal Position Sensor Learn .

5. With the transmission in neutral and clutch pedal fully pressed, attempt to start the vehicle.

The PCM CNTRL relay should click and the engine should begin cranking.

Circuit/System Testing

1. Ignition OFF, disconnect the PCM CNTRL relay.

2. With the ignition OFF and the scan tool disconnected, open and close the drivers door, and

wait 30 seconds. Test for less than 1.5 ohms between the ground circuit terminal 85 and
ground.

If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 30 and ground.

If the test lamp does not illuminate, test the B+ circuit for a short to ground or an
open/high resistance.

4. Ensure the parking brake is applied and the transmission is in PARK. Momentarily install a

2008 Hummer H3

2008 ENGINE Engine Electrical - H3

40 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal
87. The starter solenoid should engage and the engine should begin cranking.

If the solenoid does not engage, test the starter control circuit for a short to ground or
an open/high resistance. If the circuit tests normal, test or replace the starter motor.

5. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal

85.

6. With the clutch pedal fully pressed and the transmission neutral, cycle the ignition between

the OFF and CRANK position. The test lamp should turn ON and OFF when changing
between the commanded states.

If the test lamp is always ON, test the control circuit for a short to voltage. If the
circuit tests normal, replace the ECM.

If the test lamp is always OFF, test the control circuit for a short to ground or an
open/high resistance. If the circuit tests normal, replace the ECM.

7. If all circuits test normal, test or replace the PCM CNTRL relay.

Component Testing

Relays

1. Ignition OFF, remove the relay.

2. Test for 60-180 ohms between terminals 85 and 86.

If not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

30 and 86

30 and 87

30 and 85

85 and 87

If not the specified value, replace the relay.

4. Install a 20A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper

wire between relay terminal 86 and ground. Test for less than 2.0 ohms between terminals
30 and 87.

If greater than specified range, replace the relay.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

2008 Hummer H3

2008 ENGINE Engine Electrical - H3