Instrument Cluster Description and Operation: Speedometer

The instrument panel cluster (IPC) displays the vehicle speed based on information from the engine control module (ECM). The engine control module (ECM) calculates the vehicle speed from the vehicle speed sensor (VSS) input. The ECM sends a serial data message to the BCM indicating the vehicle speed. The instrument panel cluster (IPC) displays the vehicle speed as received from the BCM via serial data circuit.

The speedometer defaults to 0 km/h (0 mph) when any of the following occur:

• The ECM detects a malfunction in the vehicle speed sensor.
• The BCM detects a loss of serial data communications with the ECM.
• The IPC detects a loss of serial data communications with the BCM.