Speedometer and/or Odometer Inaccurate or Inoperative

SPEEDOMETER AND/OR ODOMETER INACCURATE OR INOPERATIVE

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

CIRCUIT/SYSTEM DESCRIPTION
The instrument panel cluster (IPC) displays the vehicle speed based on the information from the engine control module (ECM). The ECM converts the data from the vehicle speed sensor to a 4000 pulses/mile signal. The PCM sends the vehicle speed information via GMLAN serial data circuit to the body control module (BCM). The BCM sends the GMLAN message to the IPC in order to control the speedometer gage and display the vehicle speed and miles traveled.

DIAGNOSTIC AIDS
Check for the following DTCs:
- DTC B1000
- DTC B1009
- DTC U2100
- DTC U2103
- DTC U2105-U2199

CIRCUIT/SYSTEM TESTING
1. Ignition OFF, raise the vehicles drive wheels.
2. Engine ON, transmission in drive, verify the scan tool Vehicle Speed Sensor parameter matches the speedometer display.
- If the Vehicle Speed Sensor parameter does not match the speedometer display, replace the IPC.
- If the odometer is not operating properly, replace the IPC.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

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