Description & Operation: Speedometer/Odometer

The Vehicle Speed Sensor (VSS) generates an AC signal with frequency proportional to vehicle speed. This signal goes to a VSS buffer, which converts the signal to a square wave. This signal is interpreted by the speedometer and cruise control system as vehicle speed. On 3.1L, the VSS buffer is a separate component; on 3.8L it is incorporated into the Powertrain Control Module (PCM).