Vehicle Speed Sensor/Transducer - Cruise Control: Description and Operation

The vehicle speed sensor (VSS) is mounted to the automatic or manual transmission and produces an alternating current (AC) signal. The frequency of this signal is proportional to the speed at which the automatic transmission output shaft rotates, which in turn, is proportional to the speed of the vehicle.

The AC signal produced by the VSS is supplied to the powertrain control module (PCM).

The PCM internally converts the AC signal to a 4,000 pulses per mile signal. It then delivers that signal to the cruise control module and speedometer.