Ford F7RZ-7H103-BA Sensor Assy - Engine Speed

Before starting your repairs, check the wiring from 2000 models onwards if sensor testing and the engine control unit show the sensors working fine but the driveability problems remain. If your first checks don't fix a problem, ask for help from your dealer's service department or a professional vehicle repair center. Located on the transmission and controlling the speed sensor, the sensor known as VSS produces AC voltage waves, similar to a sine wave, to show how fast the car is moving. An additional sensor at the differential top also helps make this happen. The PCM uses this input to control different engine and transmission functions, and provides power for your car's speedometer reading. The VSS sensor has two problems: it can keep the car from performing well, and when EEC sees the sensor isn't working, it sends codes to troubleshoot. To test the VSS sensor, unplug the connector, start the car with the ignition on, and measure between the sensor connector and ground. Normal reading should be 1.5 volts. When you spin the gear on the sensor and it doesn't pick up voltage, then the sensor needs to be replaced. Before you can fix the sensor, lift your vehicle high enough so there's no dangerous drop, detach the electrical wire from the VSS, remove the clamp and bolt holding it in place, and carefully pull the VSS out of the transmission. Measure the O-ring and get a new one to place inside of the sensor if the old ring looks damaged. You put the sensor back into place just the opposite way you took it out.

Disconnect the cable from the negative battery terminal. Raise the vehicle and place it securely on jackstands. On 4WD models, remove the front driveshaft. The OSS sensor is located on the upper left side of the transmission, at the rear. Note that on some later models, there are three speed sensors on the upper left side of the transmission. The OSS sensor is the rear one. Disconnect the electrical connector from the OSS sensor. Remove the OSS sensor retaining bolt. If you're planning to reuse the old OSS sensor, remove and discard the old 0-ring. Before installing the new 0-ring, lubricate it with petroleum jelly. Installation is the reverse of removal. Be sure to tighten the OSS sensor bolt securely.

Disconnect the negative battery terminal and raise the vehicle on jack stands. Disconnect its electrical connector and remove the retaining bolt. If reusing, discard the old O-ring and lubricate the new one. If installing a new sensor, lubricate its O-ring. Reverse these steps for installation.

Check the wiring harness and connectors between the sensor and the PCM for an open or short circuit.

Raise the vehicle and place it securely on jackstands.