BRAKE CONTROL SYSTEM

FUNCTION OF MAIN COMPONENTS

Component		Function
Brake Actuator Assembly	Skid Control ECU	Judges the vehicle driving condition based on the signals from each sensor and switch, and sends the brake control signals to the brake actuator.
	Solenoid Valves	The hydraulic circuit has 2 master cylinder cut solenoid valves, 2 reservoir cut solenoid valves, 4 pressure holding solenoid valves and 4 pressure reduction solenoid valves.1 The hydraulic circuit has 4 pressure holding solenoid valves and 4 pressure reduction solenoid valves.2 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 the wheel cylinders.
	Pump Motor	Drives the pumps inside the brake actuator.
	Solenoid Relay (Built into Skid Control ECU)	Supplies power to the solenoid valves.
	Motor Relay (Built into Skid Control ECU)	Supplies power to the pump motor.
	Master Cylinder Pressure Sensor*1	Assembled in the brake actuator, detects the master cylinder pressure.
Spiral Cable with Sensor Sub-assembly*1	Steering Sensor	Detects the steering direction and angle of the steering wheel.
Airbag Sensor Assembly*1	Yawrate Sensor	The airbag sensor assembly incorporates the yawrate sensor and acceleration sensor. The yawrate sensor detects the vehicle's yaw rate. The acceleration sensor detects the vehicle's longitudinal and lateral deceleration. The airbag sensor assembly sends the detection signals from the yawrate sensor and acceleration sensor to the skid control ECU via CAN communication.
Airbag Sensor Assembly*1	Acceleration Sensor
Speed Sensors		Detect the wheel speed of each of the 4 wheels.
Stop Light Switch Assembly		Detects the brake pedal depressing signal.
Brake Pedal Load Sensing Switch*3		Detects the brake pedal depressing signal.
Parking Brake Switch Assembly		Detects when the parking brake lever is pulled up.
Brake Master Cylinder Sub-assembly	Brake Fluid Level Warning Switch	Detects the brake fluid level.
VSC OFF Switch*1		Enables the driver to select the "Normal Mode", "TRC OFF Mode", or "VSC OFF Mode".
Main Body ECU (Multiplex Network Body ECU)		Transmits the parking brake switch signal to the skid control ECU.
ECM*1		Sends the throttle position signal, accelerator pedal position signal engine speed signal to the skid control ECU. Based on the signals from the skid control ECU, controls the engine output.
Throttle Body with Motor Assembly*4	Throttle Position Sensor	Detects the throttle valve opening angle and outputs it to the ECM.
Throttle Body with Motor Assembly*4	Throttle Control Motor	Adjusts the throttle valve opening angle in accordance with signals from the ECM.
Throttle Body Assembly*5	Throttle Position Sensor	Detects the throttle valve opening angle and outputs it to the ECM.
Throttle Body Assembly*5	Throttle Control Motor	Adjusts the throttle valve opening angle in accordance with signals from the ECM.
Injector Driver*3		Receives signals from the ECM to control the injector.
Combination Meter Assembly	ABS Warning Light	Illuminates to alert the driver when the skid control ECU detects a malfunction in the ABS.
	Brake Warning Light	Illuminates to alert the driver when the skid control ECU detects a malfunction in the EBD or brake system. Illuminates to alert the driver when the brake fluid level is low. Illuminates to inform the driver when the parking brake is operated.
	Slip Indicator Light*1	Illuminates to alert the driver if the TRC or VSC system malfunctions. Blinks to inform the driver when the TRC or VSC operates.
	TRC OFF Indicator Light*1	Illuminates to inform the driver of "TRC OFF mode" or "VSC OFF mode" being selected.
	VSC OFF Indicator Light*1	Illuminates to inform the driver of "VSC OFF mode" being selected.
	Buzzer	Sounds to alert the driver when the vehicle is being driven with the parking brake still engaged.
Hazard Warning Signal Switch Assembly*1		Transmits a hazard warning light on/off request signal to the skid control ECU.

*1: Models with brake control (ABS with EBD, brake assist, TRC, VSC and hill-start assist control)

*2: Models with brake control (ABS with EBD)

*3: Models with 1AD-FTV engine

*4: Models with 1NR-FE engine

*5: Models with 1ZR-FAE, 1ZR-FE or 2ZR-FE Engine

SYSTEM CONTROL

Table of System Control

The brake control system has the following system/functions:

Control	Outline
Anti-lock Brake System (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)	EBD control utilizes ABS, realizing proper brake force distribution between the front and rear wheels in accordance with the driving conditions. In addition, during braking while cornering, it also controls the brake forces of the right and left wheels, helping maintain vehicle stability.
Brake Assist*	The primary purpose of brake assist is to provide supplementary brake force to assist a driver who cannot generate a large brake force during emergency braking, thus helping ensure the vehicle's braking performance.
Traction Control (TRC)*	Helps restrain the slippage of the drive wheels if the driver depresses the accelerator pedal excessively when starting off or accelerating on a slippery surface.
Vehicle Stability Control (VSC)*	Helps restrain sideways slippage of the vehicle during a strong understeer tendency or strong oversteer tendency while cornering.
Engine Output Control during TRC or VSC Operation*	Transmits an engine output control signal from the skid control ECU to the ECM to limit the engine output while the TRC or VSC is being activated.
Hill-start Assist Control*	When starting uphill, this control maintains the brake hydraulic pressure to the 4 wheels, in order to momentarily prevent the vehicle from descending backward.
Emergency Brake Signal*	In the case of emergency braking, the emergency brake signal flashes the hazard warning lights to alert the drivers in following vehicles.

*: Models with brake control (ABS with EBD, brake assist, TRC, VSC and hill-start assist control)

FAIL-SAFE

If a failure occurs in the skid control ECU, sensors, or brake actuator assembly, the system continues performing 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 DTCs and check function, refer to the Repair Manual.