Gasoline Engines

The Vehicle Speed Sensor (VSS) at the transmission generates the vehicle speed signal. This signal is then translated by the Vehicle Control Module (VCM). The VSS mounts to the automatic transmission assembly and produces an AC signal. The frequency of this signal equals the transmission output shaft speed.

The AC signal is sent to the VCM to be amplified and convened to a digital square wave that represents the vehicle speed in terms of pulses per mile. The VCM provides a 4,000 pulses per mile signal to the cruise control module and the speedometer in the instrument cluster.