BMW 840Ci ABS Control Module Replacement Cost

The ABS system is designed to keep the brakes from locking up on one of the 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 to control the amount of pressure that is being applied when the driver depresses the brake pedal.

A failing ABS control module can turn on the ABS light and disable the Traction and Stability Control Systems (if equipped). In some cases, the speedometer will stop working and the Check Engine Light will come on.

A malfunctioning ABS control module can cause abnormal braking behavior when braking at low speeds.

A loose or poor connection to ABS control module can turn on an ABS dashboard light.

Generally, if the ABS control module fails, the brakes will still function, however, the vehicle will not have skid protection in a turn, under hard acceleration, during hard braking, or if any of the wheels leave the tarmac. ABS, traction control system (TCS), and vehicle stability warning lights will illuminate on the dashboard if the ABS control module suffers failure, and trouble codes specific to the ABS system will be stored in the ECU memory.

Failure of the ABS control module does not disable the vehicle, but safety is a concern as drivers become accustomed to the road manners of their vehicle's. 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.

ABS control module replacement is less common than most other repairs. If the brake system is properly maintained, the ABS control module can be expected to last the lifetime of the vehicle in most cases.

Anti-lock braking systems are complex, and are typically diagnosed through professional computer scanning equipment, or manufacturer specific software. The technician will communicate with the ABS control module via computer, and view real-time data to determine what fault has been detected, and how the system is behaving. Finally, if the module is suspected of failure, the module inputs and outputs must be tested physically to ensure the ABS control module is at fault before confirming the diagnosis.

Once the battery is disconnected, the technician must remove all electrical connections from the module, and all brake lines from the distribution block, which is attached to the ABS control module. Once the new control module is installed, the brake system is flushed and bled, and manufacturer specific software updates will be made.