Instrument Cluster Description and Operation: Speedometer

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