Many vehicles have ABS, or anti-lock brake systems, on their cars or trucks. The sensors are designed to monitor wheel speed and to regulate your brakes so that they do not lock up under certain driving conditions. Most ABS systems typically have individual sensors mounted on or near each wheel.
However, they are all controlled by a central relay that is located in the main relay panel inside your engine compartment. If you ever have to disable your ABS system, the relay is the most direct and effective way to handle it.
Pop your hood and remove your negative battery cable.