BMW 840i Anti-lock Brake System (ABS) Diagnosis Cost

This system was designed with occupant safety in mind. The anti-lock braking (ABS) system is used to maintain wheel motion and traction while braking, accelerating or cornering on a slippery surface. This system uses the same components as the traction control system (TCS), and the functionalities of both are integrated through the ABS control module.

The ABS system is designed to keep the brakes from stopping one or more wheels while the vehicle is in motion by quickly engaging and disengaging the brakes in rapid succession until the vehicle is out of harm's way. The ABS control module is the brain of this system, and is physically attached to the brake lines, via the distribution block, to control the amount of pressure that is being applied when the driver depresses the brake pedal. Because traction control is integrated into the ABS system, the ABS module may pulse the brakes or reduce engine power during cornering to prevent wheel spin, even if the brakes are not applied.

A failure in the ABS or TCS will leave the brakes functioning normally, but without the added security of traction control and anti-lock brakes. When the ABS control module detects a fault, the ABS light, traction control light, and any manufacturer specific stability control lights will illuminate on the instrument cluster, alerting you to have the systems inspected for faults.

The vehicle can be driven with these warning lights on, since failure of the ABS or TCS does not disable the vehicle, but safety is a concern as drivers become accustomed to the road manners of their vehicles. If hard braking that is normally controlled by the ABS control module is necessary, a collision may occur. We do recommend towing the vehicle to a repair facility if the brakes feel unusual under light or normal driving conditions. Get this fixed by a RepairPal Certified Shop