Escape, Mariner, Escape Hybrid 2001-2005

Vehicle Speed Sensor



The Vehicle Speed Sensor (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.

This sensor may also be referred to as the Output Shaft Speed (OSS) sensor. The OSS sensor 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

  1. Raise and safely support the vehicle.
  3. Remove the 7 retainers and the LH splash shield.
  5. Disconnect the Vehicle Speed Sensor (VSS)/Output Shaft Speed (OSS) electrical connector.
  7. Remove the sensor bolt, then remove the sensor.
    When installing the sensor, lubricate the O-ring seal with clean transmission fluid.

  9. To install, reverse the removal procedure and note the following:
  11. Tighten the sensor mounting bolt to 9 ft. lbs. (12 Nm).


  1. Check the voltage to the Vehicle Speed Sensor (VSS)/Output Shaft Speed (OSS) sensor. Turn the ignition switch OFF and disconnect the sensor connector.
  3. Turn the ignition ON , and with the engine off, measure the voltage between VPWR and battery ground. Voltage should read 10v or more if not repair power circuit.
  5. Check the VPWR ground to the VSS/OSS sensor by measuring the resistance between PWRGND and battery ground. If the resistance is less than 5 ohms ground circuit should be okay.
  7. Inspect the VSS/OSS vehicle harness connector for damage and proper seating.
  9. If possible, carry out a wiggle test.

    Click image to see an enlarged view

    Fig. VSS/OSS sensor connector