Diagnostic Instructions
Circuit/System Description
The instrument panel cluster (IPC) displays the vehicle speed based on the information from the body control module (BCM). The engine control module (ECM) sends the vehicle speed signal information via the GMLAN serial data circuit to the BCM. The BCM
sends a GMLAN message to the IPC indicating the vehicle speed. The IPC displays the vehicle speed based on the GMLAN serial data message from the BCM.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Scan Tool Data List
Circuit/System Testing
Important: The drive wheels of the vehicle must be raised and the transmission must be placed in drive or first gear.
Start the engine, raise the vehicle drive wheels and place the transmission in drive or first gear. Verify that the speedometer value matches the scan tool Vehicle Speed parameter in the ECM Engine Data List.
| ⇒ | If the speedometer is incorrect, test or replace the IPC. |
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
Control Module References
for IPC replacement, setup, and programming
