Vehicle Speed Sensor: Description and Operation

Vehicle Speed Sensor (VSS):

PURPOSE
The Vehicle Speed Sensor (VSS) signal is used by the Powertrain Control Module (PCM) to determine vehicle speed.

OPERATION
The VSS produces AC signals proportional to vehicle speed. This signal is sent to the PCM and is converted into a vehicle speed value, stored in RAM memory. The PCM utilizes this value to aid in controlling torque converter lock-up, coolant fan control, vehicle speed control, air/fuel ratio and ignition timing.

Vehicle Speed Sensor Schematic:

CONSTRUCTION
The VSS is a variable reluctance sensor that generates a sine wave type waveform with a frequency that is proportional to the speed of the vehicle.

RELATED DIAGNOSTIC TROUBLE CODES

DTC 29/452 - PCM detected an error in the VSS output (continuous memory code).