The fundamental purpose of the anti-lock brake system is to ensure steerability, directional stability and deceleration of optimum value to the vehicle during hard braking operations performed on severe road surfaces. The system continuously monitors the rotation speed of each wheel. It includes 3 main parts wheel speed sensors electronic control unit ECU hydraulic unit. The control unit receives variable voltage signals from each of the four wheel speed sensors. It monitors these signals to check whether any of the wheels are about to lock up. The hydraulic unit can then reduce the brake pressure via electrically operated solenoid valves. When there is problem with the ABS system, a warning light "ABS" will glow on the dashboard of the vehicle. Power loss is usually due to defective wiring harness. Most of the ABS wiring harnesses have undergone wear and tear due to chafing or damage. Therefore, visually check removable wiring harnesses close to wheel area. Preliminary checks for troubleshooting may include checking the level of the brake fluid, verifying secure electrical connections, checking fuses, and inspecting wiring harnesses. If you find that these inspections do not help, it is advised to get it checked by a technician. To remove or install the wheel speed sensor, you must first loosen the wheel lugs followed by raising and removing the wheel. With the ignition switched off, trace and disconnect the sensor wiring, disconnect the electrical connector, and remove the mounting bolt to take out the sensor. The process of reinstallation is in reverse order that creates the mounting bolt of the attachment to secures.