A wheel speed sensor is used by the anti-lock brakes to determine if a wheel is moving at a different speed than the others in order to control the anti-lock brake or traction control functions. Some makes and models use a single sensor on a single wheel for the speed signal. Some vehicles that have anti-lock brakes use the wheel speed and the transmission output to determine any faults. Most models that do not have anti-lock brakes use the transmission output for the speed signal.
If the wheel speed sensor has broken, there will usually be dashboard lights for the ABS or traction control systems illuminated. The ABS system will likely not function properly.
Part 1 of 1: Replacing the wheel speed sensor
- Allen set metric and standard sockets
- Assorted pliers
- Assorted screwdrivers
- Breaker bar ½ inch drive
- Brass hammer
- Combination wrench set, metric and standard
- Disposable gloves
- Emery cloth/sandpaper
- Floor jack and jack stands
- Metric and standard socket set ½ inch drive
- Pry bar
- Ratchet ? drive
- Socket set metric and standard ? drive
- Socket set metric and standard ¼ drive
- Torque wrench ? or ½ drive
- Torx socket set
- Wheel socket set ½ inch drive
Step 1: Prepare your work area. Make sure the vehicle is on a level, safe surface, and you have set the parking brake.
Step 2: Loosen the lug nuts. Use a ½ inch drive breaker bar and a lug nut socket set to loosen all the lug nuts before you jack the vehicle up in the air.
Step 3: Jack the vehicle up and use jack stands. Jack the vehicle up and put it on jack stands. Place the wheels off to the side, away from the work area.
Be sure to jack the vehicle up in the correct location; usually on the sides underneath there are pinch welds you can use to jack from. Then make sure you place the stands on the body or frame and lower it down onto the stands.
Step 4: Remove the old wheel speed sensor. In some cases, you may have to remove the brake pads and rotors in order to get a clear view of the wheel speed sensor. Once it is visible, you can remove the bolt that holds the sensor onto the hub/knuckle.
Next, remove any clips or hold downs that are securing the sensor wiring to the vehicle's chassis/body. Once you have done that, unplug it so you can remove it completely from the vehicle. Use some emery cloth or sandpaper to clean off any rust in the areas where the new sensor will be going to ensure it fits easily.
Step 5: Install the wheel speed sensor and brake parts. Work in the reverse order of the way you removed everything. Start by plugging in the new connector and then routing the harness back so it is secured to the body/chassis. Then insert it into the hub/knuckle.
If you needed to remove the brakes, reinstall the rotor and brake caliper bracket along with your brake pads, and make sure you torque everything to factory specs.
Step 6: Reinstall the wheels. Place the wheels back onto the hubs using the lug nuts. Snug them all down with a ratchet and socket.
Step 7: Jack the vehicle back off the jack stands. Place the jack in the correct spot under the vehicle and jack the car up until you can remove the jack stands. Then you can lower the vehicle back onto the ground.
Step 8: Torque the wheels. Most cars use a torque from 80 ft lbs to 100 ft lbs. SUVs and trucks usually use anywhere from 90 ft lbs to 120 ft lbs. Use a ½ inch torque wrench and torque the lug nuts to the proper specification.
Step 9: Test drive the vehicle. After the wheel speed sensor is replaced, the ABS and traction control lights should go out. In the event that they don't, you will need to take it to a certified mechanic to have them reset the vehicle’s computer.
To test drive, go down a safe road where you can speed up and hit your brakes hard to try and engage your ABS and make sure it is working properly.
Replacing a wheel speed sensor is a very straightforward job with the right tools and knowledge. But if it’s something you don’t want to tackle on your own, the professional mechanics at YourMechanic can complete the wheel speed sensor replacement for you.
This article originally appeared on YourMechanic.com as How to Replace a Wheel Speed Sensor and was authored by Chris Young.