For 1990-2009 cars

### Diagnostic Fault Information

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

### Circuit/System Description

The instrument panel cluster (IPC) displays the engine speed based on information received from the engine control module (ECM). The ECM sends the engine 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 to display the engine speed.

### 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. Using a scan tool, ensure no other DTCs are set as current. If any DTCs are set as current rectify these DTC first.
2. Ignition ON, perform the tachometer gauge sweep test with the scan tool.

⇒ | If the tachometer gage does not sweep from its low to high position, replace the instrument panel cluster (IPC).

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for IPC replacement, setup and programming.