Speedometer and Odometer

The Vehicle Speed Sensor (VSS) is a gear-driven permanent magnet generator housed in the vehicle's transaxle. This sensor generates a sine wave output with a frequency proportional to vehicle speed. The Powertrain Control Module (PCM) converts this signal to an output that is switched to ground at a frequency of 4000 pulses per mile. This signal (circuit 389) drives the speedometer and odometer and is used by various other components.