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

This diagnostic procedure applies to serial data gages located in the instrument panel cluster (IPC) which includes the speedometer, tachometer, engine coolant temperature gage and volt gage (if equipped).

Reference Information

Schematic Reference

    •  Instrument Cluster Schematics
    •  Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

    •  Instrument Cluster Description and Operation
    •  Engine Control Module Description

Electrical Information Reference

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Important: If the suspect gage is the speedometer, the drive wheels of the vehicle must be raised and the transmission must be placed in drive or first gear.

  1. Ignition ON, perform the IPC gage sweep test with the scan tool. Verify that all the gages sweep from their low to high position.
  2. If any of the gages do not sweep from their low to high position, replace the IPC.
  3. Engine ON, transmission in drive or first gear, verify the scan tool Vehicle Speed parameter matches the speedometer display.
  4. If the Vehicle Speed parameter does not match the speedometer display, test or replace the IPC.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for the IPC replacement, setup, and programming