How to Check Wheel Speed Sensors. An ABS braking system has become a common safety feature included in new cars. If your ABS warning light is illuminated there is a possibility that the wheel speed sensors are malfunctioning. Luckily wheel speed sensors are relatively easy to check regardless of car model, due to the ABS braking system's streamlined nature. With the help of your owner's manual and the right instructions, you'll be able to accurately check the ABS wheel speed senors to determine which need replacing in a few hours' time.
Park your car on a level surface. Consult your owner's manual for the location of the wheel speed sensors. If your car is front-wheel drive, the wheel speed sensors will be located at the two front tires. On rear-wheel drive vehicles, find the sensors at the rear wheels. If you have lost your owner's manual ownersmanualsource.com offers hundreds of free owner's manuals in PDF file format (see Resources).
Jack up your car and lower it onto jack stands. Remove all the wheel lugs secure the wheel onto the car using a lug wrench. Place two hands onto the wheel and firmly tug it away from the car.
Locate the ABS wheel speed sensor cable. It should be visible directly above the brake rotor in the wheel arch. Disconnect the cable at the two-pin connection point.
Locate the wheel speed sensor. It should be visible and bolted onto the wheel crown directly behind the wheel hub. Set your digital multi-meter to Ohms. Connect the two digital multi-meter probes directly to the wheel speed sensor's connection point and take note of the value.
Turn the wheel hub using your free hand while maintaining contact on the wheel speed sensor with the digital multi-meter probes (having a helper for this step is ideal). Take note of the resistance changing on the digital multi-meter. If the value does not change at all the sensor is damaged and will need to be replaced. If the resistance changes dramatically to a very high value, (consult your owner's manual for the specific range of resistance you ought to expect for your particular wheel speed sensor) the sensors has a high resistance coil and will need to be replaced.
Repeat steps one through five to check all additional wheel speed sensors on your car.