F 250 4WD Super Duty V8-6.4L DSL Turbo (2008)
Vehicle Speed Sensor: Description and Operation
Vehicle Speed Sensor (VSS)
Vehicle Speed Sensor (VSS)
The VSS is a variable reluctance or hall-effect sensor that generates a waveform with a frequency that is proportional to the speed of the vehicle. If the
vehicle is moving at a relatively low velocity, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a
signal with a higher frequency. The PCM uses the frequency signal generated by the VSS (and other inputs) to control such parameters as fuel injection,
ignition control, transmission/transaxle shift scheduling, and torque converter clutch scheduling.
