Wheel Speed Sensor: Description and Operation

Fig. 3 Wheel Speed Sensor:

Fig. 4 Rear Wheel Speed Sensor:

The sensor sends wheel speed information to the ECU where the speed signals are used to determine when anti-lock control is required. Each wheel speed sensor consists of a magnet surrounded by a coil of wire. Mounted next to each sensor is a toothed ring that rotates along with the brake disc.


As each tooth passes, the magnetic field in the wheel sensor is strengthened momentarily. This field strength change, repeated as each tooth passes the sensor, induces voltage in the wheel speed sensor coil and coaxial cable. The ECU compares the frequency of the AC signals from the wheel speed sensors to detect rapid wheel deceleration, indicating possible wheel locking.


NOTE: Tire size determines the number of teeth on the front reluctor ring. It's therefore important that the vehicle be equipped with the original equipment tire sizes. Changing tire size could affect system function.

NOTE: Always route these cables in exactly the same position as original manufacture. Electronic noise from improper cable routing can cause improper signals to be sent to the ECU.