Speedometer Head: Description and Operation

Speedometer

The vehicle speed signal (VSS) is generated in the anti-lock brake system (ABS) and sent to the powertrain control module (PCM) through hardwired circuitry. The PCM transmits the VSS data to the instrument cluster over the high speed controller area network (HS-CAN) communication bus. If the instrument cluster fails to receive the VSS input from the PCM, the instrument cluster indicates 0 km/h (O mph) on the speedometer.