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 engine coolant temperature as determined by the engine control module (ECM). The ECM sends the temperature data via high speed GMLAN serial data to the body control module (BCM). The BCM then sends the information via low speed GMLAN to the IPC in order to display the engine temperature.

Reference Information

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Displays and Gages Connector End Views

Description and Operation

Instrument Cluster Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

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 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