Wheel Speed Sensor: Description and Operation

It consists of a sensor and a rotor. The sensor is attached to the knuckle on the front wheels and to the rear axle case on the rear differential.
The rotor is press-fit in the axle shaft.
The flux generated from electrodes magnetized by a magnet in the sensor varies due to rotation of the rotor, and the electromagnetic induction generates alternating voltage in the coil. This voltage draws a "sine curve" with the frequency proportional to rotor speed and it allows detection of wheel speed.