Circuit Operation

The vehicle speed sensor generates a signal that is proportional to vehicle speed. The signal produced is a sine wave, which the Powertrain Control Module (PCM) processes into a square wave to supply inputs to the speedometer, the Multi-Function Chime (MFC)
Module and the Computer Command Ride (CCR) Controller (if equipped).

The PCM takes the voltage pulses from the vehicle speed sensor, through the PPL and YEL wires, and uses them to close a solid-state output terminal is switched to ground at a rate that is proportional to vehicle speed.