ABS Wheel Speed Sensor Inspection
ABS-equipped vehicles contain wheel speed sensors mounted on the suspension and steering knuckles. The tone rings for these speed sensors spin with the hub or CV axle.
A loose bearing can cause the ring to wobble and damage the wheel speed sensor's tip. This damage results in an ABS warning light. Scanning the system for a fault code points to the faulty circuit. Sometimes mud or road debris gets into the gap or between the tone sprockets creating a problem with the signal.
Inspect the wheel bearings by grasping the tire at the top and bottom and rocking it back and forth. Excessive play indicates a loose wheel bearing. Faulty wheel bearings make a growling or whining sound that increases with vehicle speed and while turning.