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 the CAN serial data circuit to the body control module (BCM). The BCM sends the CAN message to the IPC in order to control the engine temperature gage and display the engine temperature.

Reference Information

Schematic Reference

Starting and Charging Schematics

Connector End View Reference

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

Circuit/System Verification

  1. Verify that the following DTCs are not set: U0100, U0155, U2105, P0117.
  2. If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.
  3. Perform the Coolant Gage Sweep test. The engine coolant gage should sweep from the minimum to maximum positions.
  4. If the gage does not sweep properly, replace the IPC.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for instrument panel cluster replacement, setup, and programming