Anti-Lock Brake System System Description
Brake. Camry. Acv40 Gsv40
SYSTEM DESCRIPTION
ABS with EBD OPERATION
FAIL SAFE FUNCTION
INITIAL CHECK
FUNCTION OF COMPONENTS
Anti-Lock Brake System -- System Description |
- HINT:
- The skid control ECU is located within the brake actuator assembly.
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.
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.
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.
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 (CAMRY_ACV40 RM000001JBB02KX.html).
When the vehicle speed first becomes approximately 6 km/h (4 mph) or more after the ignition switch is turned to the ON position, 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.
Components
| Function
|
Brake actuator assembly
| - Composed of the holding solenoid valve, pressure reduction solenoid valve, pump motor, reservoir, etc., and adjusts the hydraulic pressure applied to each wheel cylinder.
- Houses the skid control ECU.
|
Skid control ECU
| Processes the signals sent from each sensor to control ABS and EBD.
|
Speed sensor
| Detects speed of each wheel and inputs the data into the skid control ECU.
|
Master cylinder
| Generates pressure according to pedal effort.
|
Stop light switch
| Illuminates the stop light when the brake pedal is depressed. (Sends a brake on signal to the skid control ECU)
|
Solenoid relay
| - Supplies power to each solenoid.
- Housed in the skid control ECU.
|
Motor relay
| - Supplies power to the pump motor.
- Housed in the skid control ECU.
|
ABS warning light
| - Comes on to inform the driver that a malfunction in the ABS and EBD has occurred.
- Blinks to output DTC.
|
BRAKE warning light
| - Comes on to inform the driver that the parking brake is on when the system is normal or the brake fluid level has decreased.
- Comes on to inform the driver that a malfunction in the EBD has occurred.
|
