NOTE: The VSS is no longer installed on newer vehicles with manual transmission. On these vehicles the vehicle speed is provided via the ABS (Anti-lock Brake System).
The VSS works on the Hall-effect principle of operation (not on the Transit) and delivers a square-wave voltage signal whose frequency is proportional to the current vehicle speed.
The signal is used:
โข to calculate the selected gear,
โข as information for the trip computer,
โข as information on vehicle speed for the instrument cluster,
โข as information for the speed control system incorporated in the PCM.
Effects of faults
increased idling speed
uncomfortable juddering when changing gears
Diagnosis
The input signals of the sensor are continuously checked
to ensure that they are functioning correctly.