Normal Operation and Fault Conditions
WARNING: This page is about a different car, the 2018 Ford Focus. However, it is still accessible from the selected car via links, so may be relevant.
The wheel speed sensor uses the tone ring to generate a square wave signal proportional to wheel speed which is sent to the ABS module. The front wheel bearing, rear axle shafts, tone rings and wheel speed sensors must be undamaged and free from any contamination to produce a clean signal for use by the ABS module. Also, all 4 tires and wheels must be of the same manufacturer recommended size for the wheel speed sensor to generate an accurate wheel speed signal.