BRAKE CONTROL SYSTEM

FUNCTION OF MAIN COMPONENTS

Component		Function
Brake Actuator Assembly	Solenoid Valve Master Cylinder Cut Solenoid Valve Reservoir Cut Solenoid Valve	Change the fluid path based on the signals from the skid control ECU during the operation of the brake control system functions in order to control the fluid pressure applied to each wheel cylinder.
	Master Cylinder Pressure Sensor	Assembled in the brake actuator, detects the master cylinder pressure.
	Skid Control ECU	Judges the vehicle driving condition based on the signals from each sensor, and sends the brake control signals to the brake actuator.
	Motor Relay	Supplies power to the pump motor.
	Solenoid Relay	Supplies power to the solenoid valves.
Combination Meter Assembly	Brake Warning Light	Illuminates to alert the driver when the skid control ECU detects a malfunction in the EBD. Illuminates to alert the driver when the brake fluid level is low.
	ABS Warning Light	Illuminates to alert the driver when the skid control ECU detects a malfunction in the ABS.
	Slip Indicator Light	Blinks to inform the driver when the TRC and VSC are operational. Illuminates to alert the driver when the skid control ECU detects a malfunction in the TRC or VSC.
	VSC OFF Indicator Light	Illuminates to inform the driver when VSC OFF mode is selected.
	Master Warning Light	Illuminates when the warning message is displayed in the multi-information display.
	Multi-information Display	Displays an information message when TRC OFF mode is selected. Displays a warning message when the skid control ECU detects a malfunction in the ABS or EBD.
	Multi Buzzer	Sounds together with a message display on the multi-information display during a system malfunction.
Combination Switch Assembly	VSC OFF Switch	Enables the driver to select "Normal Mode", "TRC OFF Mode", or "VSC OFF Mode".
Air Conditioning Control Assembly	Hazard Warning Signal Switch	Transmits a hazard warning light on/off request signal to the skid control ECU.
Brake Pedal Load Sensing Switch		Detects the brake pedal load.
Stop Light Switch Assembly		Detects the brake pedal depressing signal.
Semiconductor PWR Integration ECU	Stop Light Control Relay	Illuminates or flashes the stop lights in accordance with the signals from the stop light switch assembly and skid control ECU.
Parking Brake Switch Assembly		Detects the parking brake pedal status.
Speed Sensor		Detect the wheel speed of each of the 4 wheels.
Yawrate Sensor		Detects the vehicle's longitudinal and lateral acceleration. Detects the vehicle's yaw rate.
Steering Sensor		Detects the direction and angle of the steering wheel.
Power Steering ECU Assembly		Controls the steering assist torque based on the signals received from the skid control ECU.
Front Steering Control ECU*2		Controls the turning angle of the front wheels based on the signals received from the skid control ECU.
Absorber Control ECU*3		Controls the damping force based on the signals received from the skid control ECU.
Driving Support ECU Assembly*1		Makes a request for brake control to the skid control ECU.
ECM		Sends the throttle position signal, accelerator pedal position signal, engine speed signal etc., to the skid control ECU. Controls the engine output based on the signals received from the skid control ECU.
Main Body ECU (Multiplex Network Body ECU)		Transmits the parking brake switch signal to the skid control ECU.
Engine Stop and Start ECU*4		Sends brake request signals and brake release request signals to the skid control ECU assembly when the engine is stopped by stop and start control.
Network Gateway ECU1, 3		Relays data between buses.

*1: Models with pre-collision system

*2: Models with variable gear ratio steering system

*3: Models with adaptive variable suspension system

*4: Models with stop and start system

SYSTEM CONTROL

The brake control system has the following system/functions:

Control	Function
Anti-lock Brake System (ABS)	The ABS helps prevent the wheels from locking when the brakes are applied firmly or when braking on a slippery surface.
Electronic Brake Force Distribution (EBD)	The EBD utilizes ABS, achieving proper brake force distribution between the front and rear wheels in accordance with the driving conditions. In addition, during braking while cornering, the EBD also controls the brake forces of the right and left wheels, helping maintain vehicle behavior.
Brake Assist	The primary purpose of brake assist is to provide an auxiliary brake force to assist a driver who cannot generate a large brake force during emergency braking, thus helping ensure the vehicle's braking performance. If the brake booster malfunctions and the skid control ECU judges that the brake pedal force applied by the driver is not sufficient to ensure adequate braking force, brake assist is used to enhance the braking force.
Traction Control (TRC)	The TRC helps restrain the slippage of the drive wheels if the driver depresses the accelerator pedal excessively when starting off or while accelerating on a slippery surface.
Vehicle Stability Control (VSC)	The VSC helps restrain sideways slippage of the vehicle during a strong front wheel skid or strong rear wheel skid, which may occur while cornering.
VSC and Cooperative Control with EPS1 or VSC+2	This performs cooperative control with the power steering ECU assembly and front steering control ECU*3 in order to provide steering assist in accordance with the operating conditions of the vehicle.
Hill-start Assist Control	When starting uphill, this control maintains the brake hydraulic pressure on all 4 wheels, in order to momentarily prevent the vehicle from descending backward.
Radar Cruise Control Brake*4	When the driving support ECU assembly determines that a large deceleration is required based on the distance to the preceding vehicle and the relative vehicle speed during the dynamic radar cruise control system operation, the skid control ECU operates the brake system according to the signal from the driving support ECU assembly.
Pre-collision Brake*4	When the driving support ECU assembly determines that the possibility of a collision is high or an unavoidable collision condition exists, the skid control ECU activates the pre-collision brake assist or the pre-collision brake according to the signal from the driving support ECU assembly.
Emergency Brake Signal	In the case of emergency braking, the emergency brake signal flashes the stop lights to alert the drivers in following vehicles.

*1: Models for General countries

*2: Models for Europe

*3: Models with variable gear ratio steering system

*4: Models with pre-collision system

FAIL-SAFE

If a failure occurs in the skid control ECU, sensors, or brake actuator assembly, the system continues effecting brake control by excluding the failed area and using only the areas that are operating normally.

DIAGNOSIS

If the skid control ECU detects a malfunction in the brake control system, the warning lights or indicator light illuminate. At the same time, a Diagnostic Trouble Code (DTC) is stored in the memory of the skid control ECU.
This system has a sensor signal check (test mode) function.
For details of DTC and check function, refer to the Repair Manual.