Toyota CH-R Service Manual: System Description

Toyota CH-R Service Manual / Brake Control / Dynamic Control Systems / Vehicle Stability Control System / System Description

SYSTEM DESCRIPTION

FUNCTION DESCRIPTION

(a) Enhanced-VSC

(1) Effects cooperative control with the power steering ECU assembly in order to provide steering assist in accordance with the operating conditions of the vehicle.

(b) Anti-lock Brake System (ABS)

(1) The ABS helps prevent the wheels from locking when the brakes are applied firmly or when braking on a slippery surface.

(1) EBD control utilizes the ABS, realizing proper brake force distribution between the front and rear wheels in accordance with the driving conditions. When braking while cornering, it also controls the brake forces of the right and left wheels, helping maintain vehicle behavior.

(d) Brake Assist (BA)

(1) 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 braking performance of the vehicle.

(e) Traction Control (TRAC)

(1) The TRAC system 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.

(f) Vehicle Stability Control (VSC)

(1) The VSC system helps restrain sideways slippage of the vehicle during a strong understeer tendency or strong oversteer tendency while cornering.

(g) Hill-start Assist Control

(1) When starting uphill, this control maintains the brake hydraulic pressure to the 4 wheels, in order to momentarily prevent the vehicle from descending backward.

(h) Brake Hold System

(1) As the driver depresses the brake pedal and the vehicle comes to a stop, this function maintains the hydraulic pressure of the 4 wheels in order to keep the vehicle stopped.

(i) Trailer Sway Control

(1) If the vehicle is towing a trailer with an inappropriate hitch load trailer sway could be caused by crosswinds, imbalance caused by load, or the driver's steering. Trailer sway control helps to reduce trailer sway by controlling the engine output and the braking of each wheel.

FUNCTION OF COMPONENTS

Component		Function
Brake Actuator Assembly	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 assembly.
	Master Cylinder Pressure Sensor	Assembled in the brake actuator assembly, detects the master cylinder pressure.
	Pump Motor	Drives the pumps inside the brake actuator assembly.
	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. 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.
Skid Control ECU	ABS Motor Relay	Supplies power to the pump motor.
Skid Control ECU	ABS Solenoid Relay	Supplies power to the solenoid valves.
Speed Sensor		Detects the wheel speed of each of the 4 wheels.
Stop Light Switch Assembly		Detects the brake pedal depressing signal.
Main Body ECU (Multiplex Network Body ECU)		Transmits the parking brake switch signal to the skid control ECU.
Electric Parking Brake Switch Assembly	VSC OFF Switch	Enables the driver to select the Normal mode, TRAC off Mode, or VSC off mode.
Electric Parking Brake Switch Assembly	Brake Hold Switch	Permits the brake hold operation.
ECM		Sends the throttle position signal, accelerator pedal position signal, engine speed signal etc. to the skid control ECU. Based on the signals from the skid control ECU, controls the engine output.
Airbag Sensor Assembly	Yaw Rate and Acceleration Sensor	The airbag sensor assembly incorporates the yaw rate sensor and acceleration sensor. The yaw rate sensor detects the vehicle's yaw rate. The acceleration sensor detects the vehicle's longitudinal and lateral acceleration. The airbag sensor assembly sends the detection signals from the yaw rate sensor and acceleration sensor to the skid control ECU via CAN communication.
Steering Angle Sensor		Detects the steering direction and angle of the steering wheel.
Combination Meter Assembly	ABS Warning Light	Illuminates to alert the driver when the skid control ECU detects a malfunction in the ABS.
	Brake System Warning Light (Red Indicator)	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.
	Multi-information Display (TRAC OFF Message)	Displays the information message when TRAC off mode or VSC off mode is selected.
	VSC OFF Indicator Light	Illuminates to inform when driver of VSC off mode is selected.
	Slip Indicator Light	Blinks to inform the driver when the TRAC or VSC system is performing control. Illuminates to alert the driver when the skid control ECU detects a malfunction in the TRAC and/or VSC system.
	Brake Hold Standby Indicator Light	Illuminates to inform the driver that the brake hold standby condition has been established.
	Brake Hold Operated Indicator Light	Illuminates to inform the driver that the brake hold function is operating. Blinks to alert the driver when the skid control ECU detects a malfunction in the brake hold function.
Brake Master Cylinder Reservoir Sub-assembly	Brake Fluid Level Warning Switch	Detects the brake fluid level.
Brake Pedal Support Assembly	Brake Pedal Load Sensing Switch	Detects the brake pedal load.
Millimeter Wave Radar Sensor Assembly*1		Sends brake request signals to the skid control ECU.

*1: w/ Pre-collision System

System Diagram

SYSTEM DIAGRAM Transmitting ECU (Transmitter) Receiving ECU Signal Communication Method Skid control ECU (brake actuator assem ...

Check For Intermittent Problems

CHECK FOR INTERMITTENT PROBLEMS CHECK FOR INTERMITTENT PROBLEMS HINT: A momentary interruption (open circuit) in the connectors and/or wire harness between the sensors and ECUs can be detected us ...

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Toyota CH-R Service Manual: System Description

System Diagram

Check For Intermittent Problems

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