GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    â€¢ Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    â€¢ Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    â€¢  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The instrument panel cluster (IPC) displays the vehicle speed based on the information from the engine control module (ECM)/powertrain control module (PCM). The ECM/PCM converts the data from the vehicle speed sensor to a 4000 pulses/mile signal. The ECM/PCM sends the vehicle speed information via CAN serial data circuit to the body control module (BCM). The BCM then sends the information via class 2 serial data to the IPC to order to display the vehicle speed and miles traveled.

Diagnostic Aids

Check for the following DTCs:

    â€¢  DTC B1000
    â€¢  DTC U2100
    â€¢  DTC U2105-U2199

Reference Information

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Displays and Gages Connector End Views

Electrical Information Reference

    â€¢  Circuit Testing
    â€¢  Connector Repairs
    â€¢  Testing for Intermittent Conditions and Poor Connections
    â€¢  Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Testing

  1. Ignition OFF, raise the vehicles drive wheels.
  2. Engine ON, transmission in drive, verify the scan tool Vehicle Speed parameter matches the speedometer display.
  3. ⇒If the Vehicle Speed parameter does not match the speedometer display, replace the IPC.
  4. Verify that the odometer is operating properly.
  5. ⇒If the odometer is not operating properly, replace the IPC.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for IPC replacement, setup, and programming