System Operation
The hydraulic pump maintains a pressure between 2030 psi (143 kg/cm2 ) and 2610 psi (184 kg/cm2 ) in the accumulator and is connected by a high pressure hose to the booster chamber and a control valve.
When the brakes are applied, a scissor-lever mechanism activates the control valve. Pressure, proportional to the pedal travel, enters the booster chamber. This pressure is transmitted through the normally open solenoid valve through the proportioning valve to the rear brakes.
The same pressure moves the booster piston against the master cylinder piston, shutting off the central valves in the master cylinder. This applies pressure to the front wheel through the 2 front normally open solenoid valves. The electronic controller monitors the electromechanical components of the system.
Malfunction of the anti-lock brake system will cause the electronic controller to shut off or inhibit anti-lock brake system. However, normal power assisted braking remains. Malfunctions are indicated by one or both warning lights inside vehicle. Loss of hydraulic fluid or power boost pressure will disable the anti-lock brake system.
The 4-wheel anti-lock brake system is self monitoring. When the vehicle ignition switch is placed in the "RUN" position, the electronic controller will perform a preliminary self check on the anti-lock electrical system. This is indicated by a 3-4 second illumination of the "Check Anti-Lock Brakes" light.
During vehicle operation, including normal and anti-lock braking, the electronic controller continually monitors all electrical anti-lock functions and many hydraulic performance characteristics.
In most malfunctions in the anti-lock braking system, the "Check Anti-Lock Brakes" and/or "BRAKE" light will be illuminated. The sequence of illumination of these warning lights combined with the problem symptoms determine the appropriate diagnostic tests to perform.