VEHICLE STABILITY CONTROL SYSTEM SYSTEM DESCRIPTION


  1. FUNCTION DESCRIPTION


    1. ABS (Anti-lock Brake System)


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

    2. EBD (Electronic Brake force Distribution)


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

    3. BA (Brake Assist)


      1. The primary purpose of the brake assist system is to provide auxiliary brake force to assist the driver if the driver cannot generate a large enough brake force during emergency braking, thus helping to maximize the brake performance of the vehicle.

    4. TRC (Traction Control)


      1. The TRC system helps prevent the drive wheels from slipping when the driver depresses the accelerator pedal excessively when starting off or accelerating on a slippery surface.

    5. VSC (Vehicle Stability Control)


      1. The VSC system helps prevent the vehicle from slipping sideways as a result of strong front or rear wheel skid during cornering.

    6. A-TRC (Active Traction Control) (for 4WD)


      1. During rugged off-road driving, this system controls the brake fluid pressure that is applied to the slipping wheel and distributes the drive force that would have been lost through the slippage to the remaining wheels in order to achieve an LSD (Limited Slip Differential) effect.

    7. Downhill Assist Control (w/ Downhill Assist Control)


      1. When the downhill assist control switch is pressed, downhill assist control activates 4-wheel hydraulic pressure control in order to maintain a constant low vehicle speed without causing the wheels to become locked. Therefore, the vehicle can descend steep hills in a stable manner.

    8. Hill-start Assist Control


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

    9. 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 the load, or the driver's steering. Trailer sway control reduces trailer sway by controlling the engine output and the braking of each wheel.

  2. 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, 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 Motor Relay Supplies power to the pump motor.
    Solenoid Relay Supplies power to the solenoid valves.
    Speed Sensor Detects the wheel speed of each of the 4 wheels.
    VSC OFF Switch Switches off the TRC and VSC operation.
    Stop Light Switch Assembly Detects the brake pedal depressing signal.
    ECM

    • Sends the throttle position signal, accelerator pedal position signal and engine speed signal to the skid control ECU.

    • Controls the engine output based on the signals received from the skid control ECU.
    Airbag Sensor Assembly Yaw Rate and Acceleration Sensor

    • Detects the vehicle's yaw rate.

    • Detects the vehicle's acceleration in the forward, rearward and lateral directions.
    Spiral with Sensor Cable Sub-assembly Steering Angle Sensor Detects the steering direction and angle of the steering wheel.
    Downhill assist control switch*1 Allows the driver to turn downhill assist control on and off.
    Combination Meter Assembly ABS Warning Light

    • Illuminates to alert the driver when the skid control ECU detects a malfunction in the ABS.

    • When the rear differential lock is in the lock state, the ABS is also prohibited and the ABS warning light turns on.*5
    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.
    TRC OFF Indicator Light*3

    • Illuminates to inform the driver when TRC off mode is selected.

    • When the rear differential lock is in the lock state, the TRC is also prohibited and the TRC OFF Indicator Light turns on.*5
    Multi-information Display (TRC OFF Message)*4

    • Illuminates to inform the driver when TRC off mode is selected.

    • When the rear differential lock is in the lock state, the TRC is also prohibited and the TRC OFF message is displayed.*5
    VSC OFF Indicator Light

    • Illuminates to inform the driver when VSC off mode is selected.

    • When the rear differential lock is in the lock state, the VSC is also prohibited and the VSC OFF indicator light turns on.*5

    • When the 4WD control switch (transfer position switch) set to L4, the VSC is also prohibited and the VSC OFF indicator light turns on.*2
    Slip Indicator Light

    • Blinks to inform the driver when the TRC and/or VSC system, A-TRC (active traction control)*2, trailer sway control or downhill assist control*1 is performing control.

    • Illuminates to alert the driver when the skid control ECU detects a malfunction in the TRC and/or VSC system, A-TRC (active traction control)*2, hill-start assist control, trailer sway control or downhill assist control*1.

    • Illuminates to inform the driver when the rear differential cannot be unlocked for 2 consecutive trips.*5
    Downhill assist control indicator light*1 Illuminates to inform the driver when downhill assist control operation is possible.
    Brake Master Cylinder Reservoir Assembly Brake Fluid Level Warning Switch Detects the brake fluid level.

    • *1: w/ Downhill Assist Control

    • *2: for 4WD

    • *3: except Multi-information Display Type

    • *4: for Multi-information Display Type

    • *5: w/ Rear Differential Lock