In cars equipped with ABS, the wheel speed sensor is integral in the operation of the system, reporting the speed of the wheel back to the abs computer, which then judges if the vehicle is experiencing a brake lock-up situation. A bad ABS sensor will not only cause this system to be less effective, but also will trigger an ABS warning light in your instrument cluster. When you get an ABS warning light, it’s a good idea to first check the wiring connection for corrosion, and when you replace an ABS wheel speed sensor, you should use dielectric grease on the electrical connector to help keep the connection in good condition and protected from the elements.