Vehicle Speed Signal

The vehicle speed signal is generated by the Vehicle Speed Sensor (VSS), at the transmission and translated by the VCM.

The VSS mounts to the automatic transmission assembly and produces an AC signal. The frequency of this signal is proportional to the transmission output shaft speed. The AC signal is sent to the VCM to be amplified and converted to a digital square wave that represents the vehicle speed in terms of Pulses Per Mile (PPM). The VCM provides a 4000 PPM signal.

This 4000 PPM signal is provided to the cruise control module, and speedometer in the instrument cluster.