The anti-lock brake system is used to keep the vehicle steerable, on the right path and achieve the best possible braking in extreme conditions on most of the types of road by; measuring the speed of the rotation of each wheel and regulate the brake fluid pressure to avoid wheel locking. It consists of three main components: tire speed sensors, an electronic control unit or a central processing unit and a hydraulic unit. Each of the four wheel-speed sensors sends a variable voltage signal to the control unit, which compares these signals in order to observe whether or not a wheel is just about to lock up; the hydraulic unit will in turn change the brake pressure by means of electrically operated solenoid valves. If something is wrong, there will be an ABS warning light on the dashboard, but one should check the wiring harness of the ABS more closely, for example near each wheel, because there can be signs of wear or rubbing. Every time the warning light stays on during operation, there is a need to have the ABS system checked more closely, basic diagnostic includes checking the brake fluid level, tightening electrical connections, replacing fuses, and checking the wiring harness. In case these checks do not solve the problem, the unit demands professional diagnosis and repair by a professional technician. For wheel speed sensor removal procedure, loosening of lug nuts, raising of the vehicle, switching off the ignition, tracing the sensors wiring, detaching of the wiring, the removal of the mounting bolt and eventually the extraction of the sensor. Installation reversed the process as all parts must be tightened as much as possible.