Diagnostic Instructions
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.
Reference Information
Electrical Information Reference
Circuit/System Testing
- Ignition OFF, raise the vehicles drive wheels.
- 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
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.