ABS Wheel Speed Sensors

ABS tone wheel on a hub with wheel bearings.

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.

Wheel speed sensor.

A loose bearing can cause the ring to wobble, damaging the wheel speed sensor's tip. This damage results in an ABS warning light.

Damaged ABS sensor wire harness.

Scan the controller for fault codes. If fault codes indicate a defective sensor, inspect the harness, wiring, controller, and wheel speed sensor before replacement. Sometimes, mud or road debris gets into the gap or between the tone sprockets, creating a problem with the signal.

Wheel bearing inspection. Rock the tire back and forth.

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.