ABS Sensor Service Video

An ABS sensor, also called a wheel speed sensor, tells the anti-lock brake system how fast each wheel is turning. During a hard stop, the system watches for a wheel that slows faster than the rest. It then pulses the brakes so that the wheel does not lock up and skid.

This video shows where the sensor sits at each wheel. It also shows how the sensor reads a toothed tone ring as the wheel spins. Then it puts a clean tone ring next to a rusted one, so you can see why the signal starts to fade before the sensor fails outright.

Each sensor sends a steady stream of pulses to the ABS module, which compares all four wheels many times per second. When a signal goes weak or drops out, the module shuts the system off rather than acting on bad data. Sensor testing and replacement are part of our brake repair and safety inspection service, which covers the full anti-lock system.

The ABS warning light is the clearest sign of a sensor problem, and the traction control light often comes on with it. Some drivers feel the brake pulse at low speed on dry pavement, which is a false trigger from a weak or dirty signal. On many vehicles, the speedometer may also jump around since it can share a signal.

At Spectra Auto Services, the fault is confirmed before any part is replaced. Our technicians pull the stored code, which points to the wheel with the problem, then watch live wheel speed data. They also check the wiring for chafing where it runs past the suspension.

You get DVI photos of the sensor tip, tone ring, and harness, so you see what we see. If the light came on around the same time your brakes started to squeal, our brake pad replacement service is often the next stop.

Salt spray from winter trips on Route 15 and I-70 packs rust between the tone ring teeth, which weakens the pulse the sensor reads until the module stops trusting it. Drivers from Urbana, Walkersville, and Mount Airy bring us ABS lights that come and go for this reason.

If your ABS light is on, call Spectra Auto Services at (301) 695-5990 to book an ABS sensor test, or stop by your Frederick car care team.