Automatic Transmission

Vehicle Speed Sensor:

The Vehicle Speed Sensor (VSS) is a magnetic pulse generator driven by the transmission speedometer gear.
The VSS produces 16 AC signals per revolution and sends this signal to the Powertrain Control Module (PCM). The PCM converts this signal to a vehicle speed value and stores that value in PCM memory.
The PCM uses this value to aid in controlling torque converter lock-up, coolant fan control, vehicle speed control, air/fuel ratio, and igniting timing.