The Vehicle Speed Sensor (VSS) is a magnetic pick-up that sends a signal to the Powertrain Control Module (PCM). The sensor measures the rotation of the transmission and the PCM determines the corresponding vehicle speed.
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.
The VSS provides the PCM with information about the rotational speed of an output shaft. The PCM uses the information to control and diagnose Powertrain behavior. In some applications, the sensor is also used as the source of vehicle speed. The sensor may be physically located in different places on the vehicle, depending upon the specific application. The design of each speed sensor is unique and depends on which Powertrain control feature uses the information that is generated.
Removal & Installation
- Position the vehicle on a hoist, and place the automatic transmission selector into the NEUTRAL position.
Disconnect the Vehicle Speed (VSS) sensor electrical connector.
Remove the VSS sensor bolt and the sensor. To install, tighten to 9 ft. lbs (12 Nm).
- To install, reverse the removal procedure.
- Turn the ignition switch to the OFF position.
Disengage the wiring harness connector from the VSS.
- Using a Digital Volt-Ohmmeter (DVOM), measure the resistance (ohmmeter function) between the sensor terminals. If the resistance is 190-250 ohms, the sensor is okay.
Vehicle Speed (VSS) Sensor Pin Testing