Antilock Brake System

System Diagram (Part 1):

System Diagram (Part 2):

SYSTEM DIAGRAM


SYSTEM DESCRIPTION

1. SYSTEM DESCRIPTION

HINT: The skid control ECU is located within the brake actuator assembly.




a. ABS
(Anti-lock Brake System)
The ABS helps prevent the wheels from locking when the brakes are applied firmly or when braking on a slippery surface.

Operation description
The skid control ECU detects wheel lock based on speed signals it receives from the wheel speed sensors. Based on this information, the skid control ECU controls the pump motor and solenoid valves. The pump motor and solenoid valves are used to prevent wheel lock by controlling the hydraulic pressure applied to the brakes at each wheel. The ABS warning light will come on when the system is malfunctioning.




b. EBD
(Electronic Brake force Distribution)
The EBD control utilizes ABS, realizing proper brake force distribution between the front and rear wheels in accordance with driving conditions. In addition, when braking while cornering, it also controls the brake forces of the right and left wheels, helping to maintain vehicle behavior.

Operation description
The skid control ECU receives a speed signal from each wheel speed sensor, and uses these signals to detect locking of the wheels. The ECU uses this information in order to determine appropriate control of the solenoid valves. The solenoid valves control the hydraulic pressure applied to the brake cylinder at each wheel. In this way, the solenoid valves are used to control the brake power split between the front and rear, and left and right wheels. The ABS and BRAKE warning lights come on if there is a malfunction in the EBD system.

2. ABS with EBD OPERATION
a. Based on the signals received from the 4 wheel speed sensors, the skid control ECU calculates the deceleration and speed of each wheel, while monitoring for wheel lock. If wheel lock is occurring, the ECU controls the solenoid valves in the brake actuator in order to adjust the hydraulic pressure applied to the brakes at each wheel.

3. FAIL SAFE FUNCTION
a. When a failure occurs in the anti-lock brake system, the ABS warning light comes on and operation is prohibited. In addition, when a failure which disables EBD operation occurs, the brake warning light also comes on and operation is prohibited.

4. INITIAL CHECK
a. When the vehicle speed first becomes approximately 4 mph (6 km/h) or more after the ignition switch is turned on (IG), each solenoid valve and motor of the brake actuator is sequentially activated to perform an electrical check. During the initial check, the operating sound of solenoid valve and motor can be heard from the engine compartment, but this is not a malfunction.







5. FUNCTION OF COMPONENTS