Vehicle Speed Sensors

Vehicle Speed Sensor

Vehicle Speed Sensors come in several different designs depending on the manufacturer. They input vehicle speed data to the transmission control module for shift control and for other systems on the CAN like cruise control and ABS (anti-lock brakes) only to name a few. Most mount directly on the transmission or transaxle case. They send a varying frequency to a meter in the TCM indicating vehicle speed.

Vehicle Speed Sensor

They're driven by a gear located on the transmission's output shaft. The speed sensor’s driven gear can be either machined and held in place by a bolt or fastened by a clip. The driven gear is in mesh with the drive gear located on the output shaft at all times. The sensor’s case, its bore, and the output shaft gear must be inspected for damage, because this could be an underlying cause of premature driven gear wear. The driven gear is typically made of plastic, intentionally making it softer than the drive gear.

As the shaft of this sensor spins, it generates an on off signal to the vehicles PCM and TCM. The PCM converts this signal into vehicle speed. In later model vehicles this information is shared between computer systems by multiplexing. Multiplexing allows the control modules to communicate with each other on a common bus consisting of twisted pair wiring. Each control module is assigned its own frequency.

If a fault code is found, visually inspect the wiring and connectors for wear or damage. The code should in the P0500 range. The sensor can be tested with a scanner and multimeter and compared to specifications.