Speedometer
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 into an output that is switched to ground at a frequency of
4000 pulses per mile. This signal (CKT 389) drives the Speedometer and
Odometer and is used by various other components.