Principles of Operation

WARNING: This page is about a different car, the 2003 Lincoln Navigator and 2003 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

The anti-lock-brake control module receives wheel speed readings from each anti-lock brake sensor and processes this information to determine if an ABS event is necessary. The anti-lock brake sensor electrically senses each tooth of the anti-lock brake sensor indicators as it passes through the anti-lock brake sensor magnetic field.

The anti-lock brake control module continuously monitors and compares the rotational speed of each wheel and, when it detects an impending wheel lock, modulates brake pressure to the appropriate brake caliper. This is accomplished by triggering the hydraulic control unit (HCU) to open and close the appropriate solenoid valves. Once the affected wheel returns to normal speed, the anti-lock brake control module returns the solenoid valves to their normal position, and normal (base) braking resumes.

The anti-lock brake control module is self-monitoring. When the ignition switch is turned to the RUN position, the anti-lock brake control module will do a preliminary electrical check, and at approximately 20 km/h (12 mph) the pump motor is turned on for approximately one-half second. Any malfunction of the ABS will cause the ABS or anti-lock brake system (ABS) to shut off and the yellow anti-lock brake warning indicator to illuminate. However, the power assist braking system functions normally.