For 1990-2009 cars

### Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

### Circuit/System Description

The instrument panel cluster (IPC) displays the vehicle speed based on the information from the engine control module (ECM). The ECM converts the data from the vehicle speed sensor to a 4000 pulses signal. The ECM sends the vehicle speed information via high speed GMLAN serial data circuit to the body control module (BCM). The BCM then sends the information via low speed GMLAN to the IPC to order it to display the vehicle speed and kilometres travelled.

### Reference Information

#### Schematic Reference

Instrument Cluster Schematics .

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing .

• | Connector Repairs .

• | Testing for Intermittent Conditions and Poor Connections .

• | Wiring Repairs .

#### Scan Tool Reference

Control Module References

### Circuit/System Testing

1. Ignition OFF, raise the vehicles drive wheels.
2. Have an assistant turn the wheel, Verify the scan tool Vehicle Speed Sensor parameter matches the speedometer display.

⇒ | If the Vehicle Speed Sensor parameter does not match the speedometer display, replace the IPC.

3. Verify that the odometer is operating correctly.

⇒ | If the odometer is not operating correctly, replace the IPC.

### Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for IPC replacement, setup and programming.