Instrument Cluster Description and Operation: Speedometer

The IPC displays the vehicle speed as determined by the ECM. The IPC calculates the mileage based on the GMLAN vehicle speed information from the ECM. The IPC receives vehicle speed information from the BCM via a GMLAN serial data message. The speedometer defaults to 0 km/h (0 mph) if the IPC detects a loss of GMLAN communications with the ECM or BCM.