A wheel speed sensor is an essential component in automobile anti-lock braking systems. It communicates the rotation and speed of each wheel to the vehicle's electronic control module which then regulates hydraulic brake pressure to keep the wheels from locking up. A failed wheel speed sensor causes malfunctions in a vehicle's ABS system. Failure to address this problem may prove costly when braking to avoid a potential accident.
No Anti-lock Brakes
According to automotive repair website AA1 Car, a malfunctioning wheel speed sensor will render a vehicle's anti-lock brakes inoperable. This will usually trigger an ABS warning light to illuminate on the vehicle's dashboard. The reason for the failure is related to the lack of information being sent to the vehicle's electronic control module. Without the wheel speed sensor, the computer can't tell if the car's wheels are locking up or not and is forced to shut down the system.
Less Wheel Traction
If the ABS warning light in your vehicle does not illuminate when a wheel speed sensor is malfunctioning, there are other symptoms to determine if the sensor is truly the problem. If your vehicle experiences a noticeable lack of traction control when braking quickly or experiences decreased handling in poor weather conditions, the wheel speed sensor may be to blame. Frayed wire connections running from the sensor to the electronic control module can also be the culprits.
ABS and Normal Brakes
A malfunctioning wheel speed sensor does not normally impact regular brake functioning -- only the anti-lock braking system. If your ABS warning and check brake lights are both illuminated on your dashboard, there is a serious problem with your vehicle. Multiple sensor failures or degradation in fluid lines may have impaired your vehicle's brake function. The vehicle should not be driven until this problem can be assessed and repaired.