Wheel Speed Sensor: Description and Operation

The front wheel speed sensor is installed to the front suspension knuckle and the rear wheel speed sensor to the rear suspension knuckle.

The front wheel sensor ring is press-fitted into the drive shaft at its wheel side (constant velocity joint side) and the rear wheel sensor ring into the wheel hub.

When the magnetic flux generated from the magnet included in the sensor varies as the sensor ring turns, an AC voltage of proportionate frequency to the wheel speed occurs in the coil also included in the sensor due to the function of electromagnetic induction. The magnitude of the voltage and frequency increase with increasing speed.

As both sensors on the front and rear wheels are unrepairable, they must be replaced when they are found in faulty condition. If the sensor ring at the front is found faulty, the joint at the wheel side (constant velocity joint side) must be replaced and that at the rear, if faulty, must be replaced as a wheel hub assembly.