Speedometer Head: Description and Operation

SPEEDOMETER

The instrument panel cluster (IPC) displays the vehicle speed based on Class 2 information from the powertrain control module (PCM) or the engine control module (ECM) or the Antilock Brake System (ABS) module. If the vehicle is equipped with ABS the speedometer defaults to 0 mph (0 km/h) or last known state if a malfunction in communication exists.