Hummer H3. Manual — part 1356

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

The instrument panel cluster (IPC) displays the engine coolant temperature as determined by the
powertrain control module (PCM). The IPC receives a serial data message from the PCM
indicating the engine coolant temperature.

Reference Information

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Displays and Gages Connector End Views

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Testing

Ignition ON, perform the engine coolant gage sweep test with the scan tool.

If the engine coolant gage does not sweep from its low to high position, replace the IPC.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Displays and Gages - H3

Control Module References for the IPC replacement, setup and programming

ENGINE OIL PRESSURE INDICATOR ALWAYS ON

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 Description

With low oil pressure, the engine oil pressure (EOP) switch closes and the signal circuit is low.
With oil pressure above 4.5 psi, the EOP switch opens and the signal circuit is high. The
powertrain control module (PCM) monitors the oil pressure switch signal circuit and sends a class
2 message to the instrument panel cluster (IPC), indicating the switch status.

Reference Information

Schematic Reference

Instrument Cluster Schematics

Engine Controls Schematics

Connector End View Reference

Displays and Gages Connector End Views

Powertrain Control Module Connector End Views

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Testing

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Displays and Gages - H3

1. Ignition OFF, disconnect the EOP switch.

2. Ignition ON, verify the scan tool Engine Oil Pressure Switch parameter is OK.

If not OK, test the signal circuit of the EOP switch for a short to ground. If the circuit
tests normal replace the PCM.

3. Ignition ON, perform the lamp test with the scan tool to turn the engine oil pressure

indicator OFF.

If the engine oil pressure indicator does not turn OFF, replace the IPC.

4. If all circuits test normal, test or replace the EOP switch.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Engine Oil Pressure Sensor and/or Switch Replacement

Control Module References for the PCM replacement, setup and programming

FUEL GAGE INACCURATE OR INOPERATIVE

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 Description

The fuel level sender changes resistance based on fuel level. The powertrain control module
(PCM) monitors the signal circuit of the fuel level sender in order to determine fuel level. When
the fuel tank is full, the sender resistance is low and the PCM senses a low signal voltage. When
the fuel tank is empty, the sender resistance is high and the PCM senses a high signal voltage. The
PCM uses the signal circuit of the fuel level sender in order to calculate the total remaining fuel
percentage in the tank. The PCM sends the fuel level percent via the class 2 serial data circuit to
the instrument cluster in order to control the fuel gage. The fuel level information is also used for
misfire and evaporative emission (EVAP) diagnostics.

Reference Information

Schematic Reference

Instrument Cluster Schematics

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Displays and Gages - H3

Engine Controls Schematics

Connector End View Reference

Displays and Gages Connector End Views

Powertrain Control Module Connector End Views

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the fuel level sensor. Install a signal

generator and instrument panel tester between the signal circuit and the low reference
circuit.

2. Ignition ON, vary the resistance on the signal generator from 40-250 ohms. Verify that the

scan tool Fuel Tank Level Remaining parameter displays the correct fuel level percent.

If the fuel level percent is incorrect, test the signal circuit and the low reference circuit
for an open/high resistance. If the circuits test normal, replace the PCM.

3. Ignition ON, vary the resistance on the signal generator from 40-250 ohms and monitor the

fuel gage.

If the gage is incorrect, replace the IPC.

4. If all circuits test normal, test or replace the fuel level sensor.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Fuel Level Sensor Replacement

Control Module References for the PCM replacement, setup and programming

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Displays and Gages - H3