Vehicle Speed Sensor Assembly and Speed Sensor Rotor

The Vehicle Speed Sensor (VSS) system is a pulse generator consisting of a speed sensor assembly, located in the case, and a toothed speed sensor rotor, which is pressed onto the final drive assembly. As the vehicle drives forward, the speed sensor rotor also rotates. This rotation produces a variable voltage signal in the pickup coil that is proportional to vehicle speed.

This information is then sent to the Powertrain Control Moduel (PCM) to indicate how fast the vehicle is traveling and to develop the shift pattern for the transmission. Other systems also use VSS information:
^ Torque Converter Clutch (TCC) apply and release
^ Cruise control system
^ Fuel delivery systems
^ Idle speed control system