The ABS system in your car is operated by a specifically designed computer unit and by braking sensors that are triggered every time the brakes are applied. The computer unit is referred to as the ABS controller. In a split second, this controller detects the presence of wheel-spin from the sensors and automatically instructs the hydraulic system to stop it. This technology isn’t 100 per cent reliable, so the computer can fail from time to time. If your wheels are spinning more than they should be, it could be a sign that your ABS controller needs replacing.