BMW 740iL ABS Hydraulic Pump Replacement Cost

Anti-lock brake (ABS) systems use hydraulic valves to send pressurized brake fluid to the service brakes in quick spurts to prevent the wheels from locking during hard braking. Since the pressure required to operate this system must be constantly regenerated, an ABS hydraulic pump is used. The ABS pump maintains the brake fluid pressure in the ABS hydraulic unit, and allows continuous operation of the ABS system without the need to repeatedly press the brakes.

When the brake system is filled with brake fluid, the ABS hydraulic unit fills at the same time, and the brake fluid inside the hydraulic unit is sufficient to actuate the brakes on demand. The ABS hydraulic pump pressurizes the fluid needed to actuate the brake system in quick intervals, and that pressure travels through the hydraulic valves when those valves are opened by the ABS control module. Depressurized brake fluid returns to the pump to be repressurized for continued use. Without the ABS pump, the driver would have to pump the brake pedal faster than humanly possible.

When the ABS hydraulic pump has failed, the driver will be prompted with an ABS system warning light, and, in most vehicles, the brake system warning light as well. The anti-lock brake system will fail to function in emergency situations, and the vehicle will feel less stable and more prone to skidding in rain, sleet, or snow.

After driving a vehicle for any length of time, the driver will become accustomed to the road manners of that vehicle, and sudden changes to safety features and driver assistance systems may lead to unpredictable operation. That being said, the normal brakes will be functional when the ABS hydraulic pump is faulty, but the vehicle will be prone to skidding in an emergency situation or during inclement weather. As a general rule, if the brake or ABS warning lights appear, or the brakes do not function properly, the vehicle should be serviced immediately.