BRAKE CONTROL SYSTEM DETAILS


  1. FUNCTION OF MAIN COMPONENTS

    Models without VSC
    Component Function
    Brake Actuator Assembly Changes 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.
    Motor Relay (Built-into Skid Control ECU) Supplies power to the pump motor.
    Solenoid Relay (Built-into Skid Control ECU) Supplies power to the solenoid valves.
    Speed Sensors Detect the wheel speed of each of the 4 wheels.
    Deceleration Sensor*1 Detects the vehicle's acceleration in forward and reverse.
    Stop Light Switch Assembly Detects the brake pedal depressing signal.
    Parking Brake Switch Detects the parking brake lever status.
    Brake Fluid Level Warning Switch Detects the brake fluid level.
    Transfer Indicator Switch (L4 Position)*2 Detects the L4 position condition.
    Transfer Indicator Switch (4WD Position)*3 Detects the transfer drive mode.
    A.D.D. Position Switch*4 Detects the A.D.D. shift actuator operating condition.
    Rear Differential Lock Position Switch*5 Detects the rear differential lock actuator operating condition.
    Combination Meter Assembly ABS Warning Light Lights up to alert the driver when the skid control ECU detects a malfunction in the ABS.
    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.

    • *1: 2WD PreRunner and 4WD models

    • *2: 4WD models

    • *3: 4WD models without A.D.D.

    • *4: Models with A.D.D.

    • *5: Models with differential lock shift actuator

    Models with VSC
    Component Function
    Brake Actuator Assembly Changes 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.
    Master Cylinder Pressure Sensor (Built-into Brake Actuator) Detects the master cylinder pressure.
    Motor Relay (Built-into Skid Control ECU) Supplies power to the pump motor.
    Motor Cut Relay (Built into Skid Control ECU) Cuts the power to the pump motor when the motor relay malfunctions.
    Solenoid Relay (Built-into Skid Control ECU) Supplies power to the solenoid valves.
    Speed Sensors Detect the wheel speed of each of the 4 wheels.
    Yaw Rate Sensor Assembly

    • Detects the vehicle's yaw rate.

    • Detects the vehicle's longitudinal and lateral acceleration.
    Steering Angle Sensor Detects the steering direction and angle of the steering wheel.
    Stop Light Switch Detects the brake pedal depressing signal.
    Parking Brake Switch Detects the parking brake lever status.
    Brake Pedal Load Sensing Switch Detects the brake pedal depressing force.
    VSC OFF Switch Enables the driver to select "Normal Mode", " TRC OFF Mode", or "VSC OFF Mode".
    Park/Neutral Position Switch Assembly*1 Detects the shift lever position.
    Transfer Indicator Switch (L4 Position)*2 Detects the L4 position condition.
    A.D.D. Position Switch*2 Detects the A.D.D. shift actuator operating condition.
    Rear Differential Lock Position Switch*3 Detects the rear differential lock actuator operating condition.
    Combination Meter Assembly ABS Warning Light Lights up to alert the driver when the skid control ECU detects a malfunction in the ABS.
    Brake System 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.

    • Illuminates to inform the driver when the parking brake lever is pulled up.
    Slip Indicator Light

    • Blinks to inform the driver when the TRC or VSC is operational.

    • Illuminates to alert the driver when the skid control ECU detects a malfunction in the TRC and/or VSC.
    TRC OFF Indicator Light

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

    • Illuminates together with the VSC OFF indicator light to inform the driver when VSC OFF mode is selected.
    VSC OFF Indicator Light Illuminates to inform the driver when VSC OFF mode is selected.
    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.
    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.

    • *1: Models with automatic transmission

    • *2: 4WD models

    • *3: Models with differential lock shift actuator

  2. SYSTEM CONTROL


    1. Models without VSC

      Control Outline
      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.

    2. Models with VSC

      Control Outline
      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 control 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, it 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 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 a strong rear wheel skid, either of which may occur while cornering.

    3. Anti-lock Brake System (ABS)


      1. The ABS prevents the wheels from locking during sudden braking or braking on a slippery surface. This provides the proper braking force when the vehicle slips, thus ensuring vehicle stability and excellent braking performance.

        A01EZ5JE01
        Text in Illustration
        *A Models with ABS *B Models without ABS
        *a Brake Operation - -

    4. Electronic Brake Force Distribution (EBD)


      1. This function controls the brake force that acts on the rear wheels in accordance with the changes in the vehicle conditions such as load factors or deceleration, in order to ensure excellent braking performance.

        A01EZ7OE01

      2. During cornering braking, this function controls the brake force that acts on the left and right wheels in accordance with the vehicle conditions at that time. This ensures vehicle stability and excellent braking performance.

        A01EZIQ
        Text in Illustration
        A01EZFI Brake Force A01EZJZ Control Moment

    5. Brake Assist


      1. In the brake assist, the skid control ECU calculates the speed and the amount of the brake pedal application based on the signals from the master cylinder pressure sensor and then determines the intention of the driver to make an emergency brake application. If the skid control ECU determines that the driver intends to make an emergency brake application, this function activates the brake actuator to increase the brake fluid pressure, which increases the brake force.

        A01EZI3E01

    6. Traction Control (TRC)


      1. The TRC helps prevent the drive wheels from slipping if the driver depresses the accelerator pedal excessively when starting off or accelerating on a slippery surface. Together with the hydraulic brake control of the drive wheels, the skid control ECU makes a request to the ECM to effect engine output control. This produces the drive force that suits the driving conditions, in order to ensure the proper start-off acceleration.

        A01EZ9LE01
        Text in Illustration (Driving on Road with Different Surface Friction Characteristics)
        *A Models without TRC *B Models with TRC
        *1

        ECM

        - Engine Output Control

        		 *2

        Brake Actuator Assembly

        - Hydraulic Brake Control
        *a Brake Slipping Drive Wheel - -
        A01EZ6V Slippery Surface - -

    7. Vehicle Stability Control (VSC)


      1. The following are 2 examples that can be considered circumstances in which the tires exceed their lateral grip limit. The VSC is designed to help control the vehicle behavior by controlling the engine output and the brakes at each wheel when the vehicle is under one of the conditions indicated below:

        A01EZ9RE01
        Text in Illustration
        *a Front Wheel Skid Tendency (Understeer) *b Rear Wheel Skid Tendency (Oversteer)

      2. To determine the condition of the vehicle, sensors detect the steering angle, vehicle speed, vehicle's yaw rate, and the vehicle's lateral acceleration, which are then calculated by the skid control ECU.

      3. Whether or not the vehicle is experiencing a front wheel skid is determined by the difference between the target yaw rate and the vehicle's actual yaw rate. When the vehicle's actual yaw rate is smaller than the target yaw rate (which is determined based on the vehicle speed and steering angle) that should be generated when the driver operates the steering wheel, it means the vehicle is making a turn at a greater angle than the target locus of travel. Thus, the skid control ECU determines that there is a large front wheel skid tendency.

        A01EZC9E01
        Text in Illustration
        *a Actual Locus of Travel (Actual Yaw Rate) *b Locus of Travel Based on Target Yaw Rate

      4. Whether or not the vehicle is experiencing a rear wheel skid is determined by the values of the vehicle's slip angle and the vehicle's slip angular velocity (time-dependent changes in the vehicle's slip angle). When the vehicle's slip angle is large, and the slip angular velocity is also large, the skid control ECU determines that the vehicle has a large rear wheel skid tendency.

        A01EZ8RE01
        Text in Illustration
        *a Direction of Travel of Vehicle's Center of Gravity *b Movement of Vehicle
        A01EZJZ Slip Angle - -

      5. When the skid control ECU determines that the vehicle exhibits a tendency to experience a front wheel skid or a rear wheel skid, it decreases the engine output and applies the brakes of the front or rear wheels to control the vehicle's yaw moment. The basic operation of the VSC is described below. However, the control method differs depending on the vehicle's characteristics and driving conditions.

      6. When the skid control ECU determines that there is a large front wheel skid tendency, it takes countermeasures in accordance with the extent of that tendency. The skid control ECU controls the engine output and applies the brakes of the front wheel on the outer circle of the turn and the rear wheels in order to help restrain the front wheel skid tendency.

        A01EZPK
        Text in Illustration
        A01EZFI Brake Force A01EZJZ Control Moment

      7. When the skid control ECU determines that there is a large rear wheel skid tendency, it takes countermeasures in accordance with the extent of that tendency. It applies the brakes of the front wheel on the outer circle of the turn, and generates an outward moment of inertia in the vehicle, in order to restrain the rear wheel skid tendency. Along with the reduction in the vehicle speed caused by the braking force, excellent vehicle stability is ensured. In some cases, the skid control ECU applies the brake of the rear wheels, as necessary.

        A01EZPX
        Text in Illustration
        A01EZFI Brake Force A01EZJZ Control Moment

  3. FUNCTION


    1. VSC OFF Switch


      1. The operation of the VSC and TRC functions can be stopped by the VSC OFF switch. While the vehicle is running off the shoulder of the road or running on a dirt road, the engine output control is stopped to maintain drive torque.

      2. The VSC OFF switch can select 3 modes (Normal mode, TRC OFF mode, and VSC OFF mode).

      3. Briefly pressing the VSC OFF switch in Normal mode selects the TRC OFF mode.

      4. Pressing and holding the VSC OFF switch for 3 seconds or more with the vehicle stopped selects the VSC OFF mode, disabling the TRC and VSC functions.

      5. Briefly pressing the VSC OFF switch in the TRC OFF mode or VSC OFF mode or turning the ignition switch off returns to the Normal mode.

        A01EZO4E01
        Text in Illustration
        *a Normal Mode *b TRC OFF Mode
        *c VSC OFF Mode - -
        A01EZJZ VSC OFF Switch Operation (Briefly Press) A01EZFI VSC OFF Switch Operation (Press and Hold for 3 Seconds or More)

      6. The operation of the brake control functions and the illumination state of the respective indicator lights in each mode are as follows:

        Transfer Drive Mode VSC OFF Mode Brake Control Function TRC OFF Indicator Light VSC OFF Indicator Light
        TRC VSC
        H2 Normal Mode Controllable Controllable - -
        TRC OFF Mode Not Controllable*1 Controllable Illuminates -
        VSC OFF Mode Not Controllable Not Controllable*2 Illuminates Illuminates
        H4 Normal Mode Controllable Controllable - -
        TRC OFF Mode Not Controllable*1 Controllable Illuminates -
        VSC OFF Mode Not Controllable Not Controllable*2 Illuminates Illuminates
        L4 Normal Mode Controllable Not Controllable - Illuminates
        VSC OFF Mode Not Controllable Not Controllable Illuminates Illuminates

        Tech Tips

        *1: When the vehicle exceeds a determined speed [approximately 50 km/h (31 mph)], Normal mode will operate.

        *2: When the vehicle is braking or the yaw rate is large, the VSC will operate even in the VSC OFF mode. (In this case, the engine output is not controlled.)

  4. CONSTRUCTION


    1. Brake Actuator Assembly (Models without VSC)


      1. The brake actuator assembly consists of an actuator portion and skid control ECU.

        A01EZOYE01
        Text in Illustration
        *1 Skid Control ECU *2 Actuator Portion

      2. The actuator portion consists of 3 pressure holding solenoid valves, 3 pressure reduction solenoid valves, 2 pumps and 2 reservoirs.

        A01EZAXE01
        Text in Illustration
        *1 Pressure Holding Solenoid Valve *2 Pressure Reduction Solenoid Valve
        *3 Pump *4 Reservoir
        *5 Brake Control Valve - -
        *a From Master Cylinder *b Front Brake LH
        *c Front Brake RH *d Rear Brake LH
        *e Rear Brake RH - -

    2. Brake Actuator Assembly (Models with VSC)


      1. The brake actuator assembly consists of an actuator portion and skid control ECU.

        A01EZPQE01
        Text in Illustration
        *1 Skid Control ECU *2 Actuator Portion

      2. The actuator portion consists of 2 master cylinder cut solenoid valves, 4 pressure holding solenoid valves, 4 pressure reduction solenoid valves, 2 pumps, 2 reservoirs, and a master cylinder pressure sensor.

        A01EZMYE01
        Text in Illustration
        *1 Master Cylinder Pressure Sensor *2 Master Cylinder Cut Solenoid Valve
        *3 Pressure Holding Solenoid Valve *4 Pressure Reduction Solenoid Valve
        *5 Pump *6 Reservoir
        *a From Master Cylinder *b Rear Brake LH
        *c Rear Brake RH *d Front Brake LH
        *e Front Brake RH - -

    3. Speed Sensor


      1. The speed sensor detects wheel speed and transmits the appropriate signals to the skid control ECU.

        A01EZN0E01
        Text in Illustration
        *1 Front Speed Sensor *2 Rear Speed Sensor

      2. The MRE type speed sensor is used on the models with VSC.

        A01EZE7E01

      3. The pick-up coil type speed sensor is used on the models without VSC.

        A01EZ8HE01

    4. Deceleration Sensor (2WD PreRunner Models with ABS and 4WD Models with ABS)


      1. The deceleration sensor detects the vehicle's acceleration in forward and reverse.

        A01EZR0E01
        Text in Illustration (LHD Models:)
        *1 Deceleration Sensor - -

    5. Yaw Rate Sensor Assembly (Models with VSC)


      1. This sensor has a built-in deceleration sensor.

      2. The yaw rate sensor detects the vehicle's yaw rate.

      3. The deceleration sensor detects the vehicle's longitudinal and lateral acceleration.

        A01EZSJE01
        Text in Illustration (LHD Models:)
        *1 Yaw Rate Sensor Assembly - -

    6. Steering Angle Sensor (Models with VSC)


      1. The steering angle sensor detects the steering direction and angle, and sends this information to the skid control ECU.

        A01EZKR

  5. OPERATION


    1. ABS (Models without VSC)


      1. Based on the signals received from the 4 speed sensors and deceleration sensor*, the skid control ECU calculates the speed of each wheel and the deceleration*, and checks the wheel slipping conditions. In accordance with the slipping condition, the skid control ECU controls each solenoid valve in the brake actuator in order to adjust the fluid pressure of each wheel cylinder in the following 3 modes: pressure increase, pressure holding, and pressure reduction modes.


        • *: 2WD PreRunner and 4WD models

        A01EZMJE01
        Text in Illustration
        *1 Pressure Holding Solenoid Valve *2 Pressure Reduction Solenoid Valve
        *3 Port A *4 Port B
        *a Pressure Increase Mode *b Pressure Holding Mode
        *c Pressure Reduction Mode *d To Brake Caliper or Wheel Cylinder
        *e From Brake Caliper or Wheel Cylinder - -
        Brake Actuator Operation in ABS
        Pressure Mode Increase Mode Holding Mode Reduction Mode
        Pressure Holding Solenoid Valve (Port A) Off (Open) On (Closed) ←
        Pressure Reduction Solenoid Valve (Port B) Off (Closed) ← On (Open)
        Wheel Cylinder Pressure Increases Holds Reduces

    2. ABS and EBD (Models with VSC)


      1. Based on the signals received from the 4 speed sensors and yaw rate sensor assembly, the skid control ECU calculates the speed of each wheel and deceleration, and checks the wheel slipping conditions. In accordance with the slipping condition, the skid control ECU controls each solenoid valve in the brake actuator in order to adjust the fluid pressure of each wheel cylinder in the following 3 modes: pressure increase, pressure holding, and pressure reduction modes.

        A01EZMJE01
        Text in Illustration
        *1 Pressure Holding Solenoid Valve *2 Pressure Reduction Solenoid Valve
        *3 Port A *4 Port B
        *a Pressure Increase Mode *b Pressure Holding Mode
        *c Pressure Reduction Mode *d To Brake Caliper or Wheel Cylinder
        *e From Brake Caliper or Wheel Cylinder - -
        Brake Actuator Operation in ABS and EBD
        Pressure Mode Increase Mode Holding Mode Reduction Mode
        Pressure Holding Solenoid Valve (Port A) Off (Open) On (Closed) ←
        Pressure Reduction Solenoid Valve (Port B) Off (Closed) ← On (Open)
        Wheel Cylinder Pressure Increases Hold Reduces

    3. Brake Assist


      1. In the event of emergency braking, the skid control ECU determines the driver's intention based on the speed of the pressure increase in the master cylinder determined by the master cylinder pressure sensor signal. If the skid control ECU judges the need for additional brake assist, pressure is generated by the pump in the brake actuator and directed to the wheel cylinder to apply a large amount of fluid pressure.

        A01EZSQE01
        A01EZHFE01
        Brake Actuator Operation in Brake Assist
        Item Brake Assist Not Activated Brake Assist Activated
        Pump Off On
        Master Cylinder Cut Solenoid Valve (1) Port (A) Off (Open) On*
        (2) Port (B) Off (Open) On*
        Pressure Holding Solenoid Valve (3) Port (C) Off (Open) ←
        (4) Port (D) Off (Open) ←
        (5) Port (E) Off (Open) ←
        (6) Port (F) Off (Open) ←
        Pressure Reduction Solenoid Valve (7) Port (G) Off (Closed) ←
        (8) Port (H) Off (Closed) ←
        (9) Port (I) Off (Closed) ←
        (10) Port (J) Off (Closed) ←

        Tech Tips

        *: The solenoid valve switches the hydraulic pressure between open and closed in accordance with the operating conditions by adjusting continually.

    4. TRC


      1. The fluid pressure generated by the pump is regulated by the master cylinder cut solenoid valve to the required pressure. Thus, the wheel cylinders of the drive wheels are controlled in the following 3 modes: pressure increase, pressure holding, and pressure reduction modes to control the slippage of the drive wheels. The pressure holding solenoid valve and the pressure reduction solenoid valve are turned on or off in accordance with the ABS and EBD operation patterns.

        A01EZQAE01
        A01EZHFE01
        Brake Actuator Operation in TRC
        Item Not Activated TRC Operation
        Pressure Increase Mode Pressure Holding Mode Pressure Reduction Mode
        Pump Off On ← ←
        Master Cylinder Cut Solenoid Valve (1) Port (A) Off (Open) On* ← ←
        (2) Port (B) Off (Open) On* ← ←
        Front Brake Pressure Holding Solenoid Valve (5) Port (E) Off (Open) ← On (Closed) ←
        (6) Port (F) Off (Open) ← On (Closed) ←
        Pressure Reduction Solenoid Valve (9) Port (I) Off (Closed) ← ← On (Open)
        (10) Port (J) Off (Closed) ← ← On (Open)
        Wheel Cylinder Pressure *d Right - Increases Holds Reduces
        *c Left - Increases Holds Reduces
        Rear Brake Pressure Holding Solenoid Valve (3) Port (C) Off (Open) ← On (Closed) ←
        (4) Port (D) Off (Open) ← On (Closed) ←
        Pressure Reduction Solenoid Valve (7) Port (G) Off (Closed) ← ← On (Open)
        (8) Port (H) Off (Closed) ← ← On (Open)
        Wheel Cylinder Pressure *b Right - Increases Holds Reduces
        *a Left - Increases Holds Reduces

        Tech Tips

        *: The solenoid valve switches the hydraulic pressure between open and closed in accordance with the operating conditions by adjusting continually.

    5. VSC


      1. The VSC, by way of solenoid valves, controls the fluid pressure generated by the pump and applies it to the brake wheel cylinder of each wheel in the following 3 modes: pressure increase, pressure holding, and pressure reduction modes. As a result, the tendency to front wheel skid or rear wheel skid is controlled.

        A01EZMNE01

      2. In the front wheel skid restraining control, the brake of the front wheel on the outer circle of the turn and the brakes of the rear wheels are applied. Also, depending on whether the brake is on or off and also depending on the condition of the vehicle, there are circumstances in which the brake might not be applied to the wheels even if the wheel is targeted for braking. The following diagram shows the hydraulic circuit in the pressure increase mode, as it controls the front wheel skid condition while the vehicle is making a right turn. In other operating modes, the pressure holding valve and the pressure reduction valve are turned on or off in accordance with the ABS and EBD operation patterns.

        A01EZ54E01
        Brake Actuator Operation in VSC (Front Wheel Skid Restraining)
        Item Not Activated VSC Operation
        Pressure Increase Mode Pressure Holding Mode Pressure Reduction Mode
        Pump Off On ← ←
        Master Cylinder Cut Solenoid Valve (1) Port (A) Off (Open) On* ← ←
        (2) Port (B) Off (Open) On* ← ←
        Front Brake Pressure Holding Solenoid Valve (5) Port (E) Off (Open) ← On (Closed) ←
        (6) Port (F) Off (Open) On (Closed) ← ←
        Pressure Reduction Solenoid Valve (9) Port (I) Off (Closed) ← ← On (Open)
        (10) Port (J) Off (Closed) ← ← ←
        Wheel Cylinder Pressure *d Right - - - -
        *c Left - Increases Holds Reduces
        Rear Brake Pressure Holding Solenoid Valve (3) Port (C) Off (Open) ← On (Closed) ←
        (4) Port (D) Off (Open) ← On (Closed) ←
        Pressure Reduction Solenoid Valve (7) Port (G) Off (Closed) ← ← On (Open)
        (8) Port (H) Off (Closed) ← ← On (Open)
        Wheel Cylinder Pressure *b Right - Increases Holds Reduces
        *a Left - Increases Holds Reduces

        Tech Tips

        *: The solenoid valve switches the hydraulic pressure between open and closed in accordance with the operating conditions by adjusting continually.

      3. During the rear wheel skid restraining control, the brakes of the front wheel on the outer circle of the turn are applied. Also, depending on whether the brake is on or off and also depending on the condition of the vehicle, there are circumstances in which the brake might not be applied to the wheels even if the wheel is targeted for braking. The following diagram shows the hydraulic circuit in the pressure increase mode, as it controls the rear wheel skid condition while the vehicle is making a right turn. In other operating modes, the pressure holding valve and the pressure reduction valve are turned on or off in accordance with the ABS and EBD operation patterns.

        A01EZQQE01
        Brake Actuator Operation in VSC (Rear Wheel Skid Restraining)
        Item Not Activated VSC Operation
        Pressure Increase Mode Pressure Holding Mode Pressure Reduction Mode
        Pump Off On ← ←
        Master Cylinder Cut Solenoid Valve (1) Port (A) Off (Open) On* ← ←
        (2) Port (B) Off (Open) On* ← ←
        Front Brake Pressure Holding Solenoid Valve (5) Port (E) Off (Open) ← On (Closed) ←
        (6) Port (F) Off (Open) On (Closed) ← ←
        Pressure Reduction Solenoid Valve (9) Port (I) Off (Closed) ← ← On (Open)
        (10) Port (J) Off (Closed) ← ← ←
        Wheel Cylinder Pressure *d Right - - - -
        *c Left - Increases Holds Reduces
        Rear Brake Pressure Holding Solenoid Valve (3) Port (C) Off (Open) On (Closed) ← ←
        (4) Port (D) Off (Open) On (Closed) ← ←
        Pressure Reduction Solenoid Valve (7) Port (G) Off (Closed) ← ← ←
        (8) Port (H) Off (Closed) ← ← ←
        Wheel Cylinder Pressure *b Right - - - -
        *a Left - - - -

        Tech Tips

        *: The solenoid valve switches the hydraulic pressure between open and closed in accordance with the operating conditions by adjusting continually.

  6. FAIL-SAFE


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

  7. DIAGNOSIS


    1. 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.

    2. This system has a sensor signal check (test mode) function.

    3. For details of DTC and check function, refer to the Repair Manual.