Vehicle Speed Sensor: Description and 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. The PCM provides the speed signal to the speedometer, multi-function alarm lock and lighting module, computer command ride module (if equipped), and Head-Up Display Module (if equipped).

The PCM takes the voltage pulses from the vehicle speed sensor on YEL (400) and PPL (401), and uses them to close a solid-state output switch. The output terminal DK GRN/WHT (817) is switched to ground at a rate that is proportional to vehicle speed.