Vehicle Speed Sensor: Description and Operation

Vehicle Speed Sonsor Circuit:

PURPOSE
The sensor is used by the Engine Control Module (ECM) to determine vehicle speed. The vehicle speed sensor is mounted inside the speedometer assembly.

OPERATION
As the switch rotates, continuity between terminals A and B is interrupted 4 times per revolution. This reference signal is sent to the ECM for determining vehicle speed.

CONSTRUCTION
The sensor consists of a reed switch that is closed by a rotating magnet in the speedometer.