Vehicle Speed Sensor: Description and Operation

PURPOSE
The Vehicle Speed Sensor (VSS) provides information to the Powertrain Control Module (PCM) for control of:
- Transmission Torque Converter Clutch (TCC)
- Speedometer
- Odometer
- Cruise control

CONSTRUCTION
The VSS is made up of:
- Permanent Magnet (PM) generator (coil), which is mounted on the transmission.
- Rotor (tooth), which is mounted on the output shaft in the transmission.
- VSS Buffer, which is mounted to the PCM bracket.

OPERATION
The VSS is a Permanent Magnet (PM) generator that produces a pulsing Alternating Current (AC) voltage as each rotor tooth nears the coil. As the vehicle speed increases, the number of AC voltage pulses increase and is converted by the PCM to MPH (KM/H). A VSS buffer is incorporated into the ECM for operating the instrument panel speedometer and odometer.