The vehicle speed signal is an AC signal whose frequency is proportional to the transmission output shaft speed. The vehicle speed signal is generated by the Vehicle Speed Sensor (VSS), which is mounted to the transmission assembly. The vehicle speed signal is translated by the vehicle control module (VCM).

The VCM receives the vehicle speed signal. The VCM amplifies the signal and converts the signal to digital form. The VCM, by opening and closing internal solid-state switches, then supplies a signal to the cruise control module and the speedometer. The VCM signal to the cruise control module and the speedometer pulses at a rate of 4,000 times per mile. The cruise control module and the speedometer assembly internally convert the number of pulses per mile per second to determine vehicle speed.