Instrument Panel: Operation: Speedometer/Odometer

Integrated circuits control the needle-type air core speedometer and the stepper motor-driven odometer based upon Vehicle Speed Sensor (VSS) signal. On 3.1L engine, instrument cluster applies and monitors a battery voltage signal to the VSS buffer which received an AC voltage signal from VSS.

VSS buffer pulls monitored voltage signal to zero volts approximately 4000 times per mile. This pulsed signal is interpreted by the instrument cluster as vehicle speed. On 3.8L engine, VSS buffer is built into Powertrain Control Module (PCM) and functions in the same manner as the 3.1L engine.