Vehicle Speed Sensor: Description and Operation

Vehicle Speed and Distance

Description

The PCM receives a signal from the TCM and the transaxle output speed sensor over the bus communication line.

Operation

4 Speed Automatic Transmission

The 4 speed automatic Transmission Control Module (TCM) supplies the speed input to the PCM. The PCM determines acceleration rates. The speed control software in the PCM uses vehicle speed and acceleration to control the set speed.

For more information for the 4 speed automatic transmission please refer to the Output Speed Sensor Transmission Speed Sensor

3 Speed Automatic Transmission

Vehicles with a 3 speed automatic or manual transmission have a Vehicle Speed Sensor (VSS) mounted to an adapter near the transmission output shaft. The sensor is driven through the adapter by a speedometer pinion gear. The VSS pulse signal is monitored by the PCM to determine vehicle speed and to maintain speed control set speed.