Anti-Lock Brake System, Description

WARNING:
BRAKE FLUID CONTAINS POLYGLYCOL ETHERS AND POLYGLYCOLS. AVOID CONTACT WITH EYES. WASH HANDS THOROUGHLY AFTER HANDLING. IF BRAKE FLUID CONTACTS EYES, FLUSH EYES WITH RUNNING WATER FOR 15 MINUTES. GET MEDICAL ATTENTION IF IRRITATION PERSISTS. IF TAKEN INTERNALLY, DRINK WATER AND INDUCE VOMITING. GET MEDICAL ATTENTION IMMEDIATELY.

Taurus and Sable vehicles have a 4-wheel anti-lock brake system as an option.

The system operates as follows:

• Prevents wheel lockup during an emergency stop by modulating brake pressure.
• Permits the driver to maintain steering control and stop the vehicle in the shortest possible distance under most conditions.
• During the anti-lock brake operation, the driver will sense a pulsation in the brake pedal and a clicking sound.
• The pedal effort and pedal feel during normal braking are similar to that of a conventional power brake system.

• front brake anti-lock sensor / rear brake anti-lock sensor.
• anti-lock brake control module.
• anti-lock brake hydraulic control unit.

• If the anti-lock brake module senses that a wheel is about to lock, based on brake anti-lock sensor data, it pulses the normally open solenoid valve closed for that circuit. This prevents any more fluid from entering that circuit.
• The anti-lock brake module then looks at the brake anti-lock sensor signal from the affected wheel again.
• If that wheel is still decelerating faster than the other three wheels, it opens the normally closed solenoid valve for that circuit. This dumps any pressure that is trapped between the normally open valve and the brake back to the brake master cylinder reservoir.
• Once the affected wheel returns to speed, the anti-lock brake module returns the valves to their normal condition allowing fluid flow to the affected brake.
• The anti-lock brake module monitors the electro-mechanical components of the system.
• Malfunction of the anti-lock brake system will cause the anti-lock brake module to shut off or inhibit the system. However, normal power-assisted braking remains.
• Malfunctions are indicated by a warning indicator in the instrument cluster.
• The 4-wheel anti-lock brake system is self monitoring. When the ignition switch is placed in the RUN position, the anti-lock brake module will perform a preliminary self check on the anti-lock electrical system indicated by a two second illumination of the amber ABS indicator in the instrument cluster.
• During vehicle operation, including normal and anti-lock braking, the anti-lock brake module monitors all electrical anti-lock functions and some hydraulic operations.
• In most malfunctions of the anti-lock brake system, the amber ABS indicator will be illuminated.
• Most malfunctions are recorded as a diagnostic trouble code (DTC) in the anti-lock brake module keep-alive random access memory and assist in pinpointing the component needing service.

The anti-lock brake control module is located on the hydraulic control unit located in the front of the engine compartment on the LH side of the vehicle.

The anti-lock brake control module operates as follows:

• If the anti-lock brake control module senses that a wheel is about to lock, the anti-lock brake control module activates the appropriate inlet valve in the brake pressure control valve block, which closes that valve. This prevents any more fluid from entering the affected brake.
• The anti-lock brake control module then looks at the wheel again. If it is still decelerating, the anti-lock brake control module opens the normally closed outlet valve in the brake pressure control valve block, which decreases the pressure trapped in the line.
• Impending wheel lock conditions trigger signals from the anti-lock brake control module that open and close the appropriate solenoid valves in the brake pressure control valve block. This results in moderate pulsations in the brake pedal.
• During normal braking, the brake pedal feel will be identical to a standard brake system.