GM Service Manual Online
For 1990-2009 cars only

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 vehicle voltage based on the information from the body control module (BCM). The BCM provides voltage information to the IPC via serial data.

Diagnostic Aids

The voltmeter may fluctuate between 12 and 14 volts. This is normal operation. For further information, refer to Charging System Description and Operation or refer to Voltmeter Gage under the Instrument Panel section in the owners manual.

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
    •  Scan Tool Data Definitions

Circuit/System Testing

  1. Ignition ON, perform the volt gage sweep test with the scan tool.
  2. If the volt gage does not sweep from its low to high position, replace the IPC.
  3. Ignition ON, verify the scan tool Battery Voltage parameter matches the value on the volt gage.
  4. If the value on the volt gage does not match the scan tool parameter, replace the IPC.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for IPC replacement, setup, and programming