BRAKE


  1. Toggle Lever Type Parking Brake


    1. A toggle lever type duo-servo brake mechanism is used for the parking brake to simplify the constituent parts and to achieve weight reduction.

    2. This parking brake mainly consists of parking brake shoe lever sub-assembly, parking brake shoe anchor block, shoe. When the parking brake is operated, it pulls on the cable, and this causes the parking brake shoe lever to expand the shoes via fulcrums "A" and "B".

      A01W75JC01
      *1 Parking Brake Shoe Anchor Block *2 Shoe
      *3 Parking Brake Shoe Lever Sub-assembly - -
      *a During Operation *b C-C Cross Section
  2. Electric Parking Brake System


    1. General


      • An electric parking brake system is used.

      • This system has a manual function, which allows the parking brake to be operated by the driver's switch operation, and an auto function, which allows the parking brake to be operated in conjunction with the shift lever position.

      • This system allows the parking brake to be operated by the actuator, and not only can operating force be reduced, but an improvement in convenience is aimed for by the use of the auto function.

    2. System Diagram

      A01W7MSE01
    3. Layout of Main Components

      A01W7PDC01
      *1 ECM *2 Engine Room Relay Block
      *3

      Hydraulic Brake Booster


      • Skid Control ECU

      - -
      A01W7M8C01
      *A Models with 3UR-FE Engine - -
      *1 Electric Parking Brake Switch Assembly *2 Combination Meter Assembly
      *3 Main Body ECU (Multiplex Network Body ECU) *4 DLC3
      *5

      Airbag Sensor Assembly


      • Yaw Rate Sensor

      • Deceleration Sensor

      *6 Parking Brake ECU Assembly
      *7 Parking Brake with Bracket Actuator Assembly *8 TCM
      *9 Central Gateway ECU - -
    4. Function of Main Components

      Component Function
      Parking Brake with Bracket Actuator Assembly Motor Winds and unwinds the parking brake cable based on the signals from the parking brake ECU assembly.
      Tension Sensor Detects the parking brake cable tension.
      Electric Parking Brake Switch Assembly Manual Switch
      • Sends the lock or release operation signal to the parking brake ECU assembly.

      • Switches between the manual function and auto function.

      Indicator Light Lights up to inform the driver that the parking brake has locked.
      Combination Meter Assembly Parking Brake Indicator Light
      • Lights up to inform the driver that the parking brake has locked.

      • Blinks to inform the driver that the electric parking brake system is not available.

      Brake System Warning Light (Yellow Indicator) Lights up to inform the driver that the parking brake ECU assembly detected a malfunction in the system.
      Multi-information Display
      • Informs the driver that the electric parking brake ECU assembly has a malfunction in the system.

      • Displays the switching between the manual function and auto function.

      Master Warning Light Informs the driver that the parking brake ECU assembly has a malfunction in the system.
      Multi Buzzer Sounds together with the indication of the multi-information display and the illumination of the master warning light in order to inform the driver of a malfunction in the electric parking brake system.
      Airbag Sensor Assembly Yaw Rate Sensor Detects the gradient of the road surface by detecting the inclination of the vehicle.
      Deceleration Sensor
      Parking Brake ECU Assembly Operates the parking brake based on the signals from the electric parking brake switch assembly, various ECUs, and sensors.
      Skid Control ECU
      • Detects the wheel speed.

      • Determines whether the brake pedal is depressed.

      • Sends a parking brake lock command to the parking brake ECU assembly during brake hold control.

      ECM Transmits the shift lever position to the parking brake ECU assembly.
    5. System Control


      1. Manual Function


        • When the manual switch is pulled while the vehicle is stopped, the parking brake ECU assembly will drive the motor of the parking brake with bracket actuator assembly to lock the parking brake. At this time, the parking brake ECU assembly will calculate the incline of the road surface on which the vehicle is stopped based on signals from the deceleration sensor, control the pulling force of the parking brake cable in accordance with the rotations of the motor, and generate a braking force which is responsive to the road surface on which the vehicle is stopped.

        • When a malfunction occurs in the deceleration sensor signal, the motor of the parking brake with bracket actuator assembly will be controlled in such a way as to generate the largest amount of braking force.

        • When the manual switch is pressed, the parking brake ECU assembly will drive the motor of the parking brake with bracket actuator assembly in the opposite direction, thus releasing the parking brake.

        • When the vehicle is in motion, the motor of the parking brake with bracket actuator assembly will be driven and braking force will be generated only while the manual switch is being pulled. When the manual switch is released, the motor of the parking brake with bracket actuator assembly will be driven in the opposite direction, thus reducing braking force.

      2. Auto Function


        • The manual function can be switched to the auto function via operation of the electric parking brake switch. The automatic function is activated when the driver pulls the manual switch to the Lock side at least 3 seconds to allow the parking brake to lock or release in conjunction with the shift positions. The automatic function is deactivated when the driver pushes the manual switch to the Release side at least 3 seconds.

        • When the driver moves the shift lever to P from a position other than P while the auto function is operating, the parking brake ECU assembly will control the rotation of the motor of the parking brake with bracket actuator assembly, thus locking the parking brake.

        • When the shift lever is moved from P to a position other than P while the brake pedal is depressed, the parking brake will be released.

        • The automatic function does not release the parking brake when no driving force is available, such as when the engine is stalled.

    6. Construction


      1. Parking Brake with Bracket Actuator Assembly


        • When a lock signal is received from the parking brake ECU assembly, the motor will wind up the parking brake cable by rotating the shaft, thus locking the parking brake.

        • When the motor stops rotating, operation of the clutch maintains the pulling force of the parking brake cable.

        • When a release signal is received from the parking brake ECU assembly, the motor turns in the opposite direction to reduce the pulling force of the parking brake cable, thus releasing the parking brake.

          A01W7VIC01
          *1 Clutch *2 Shaft
          *3 No. 3 Gear *4 Motor
          *5 No. 2 Gear *6 Emergency Release Cable
          *7 Emergency Release Gear *8 Equalizer
          *9 Tension Sensor *10 Parking Brake Cable

          Figure 1. Parking Brake with Bracket Actuator Assembly Operation Image

          A01W7JAC01
          *1 Motor *2 Equalizer
          *3 Shaft *4 Parking Brake Cable
          *a Parking Brake Lock *b Parking Brake Release
      2. Tension Sensor


        • A Hall IC type height control sensor has been provided. This sensor is connected to the equalizer in order to detect the motion of the parking brake cable.

        • When the equalizer is pulled to the left (as shown in the illustration below) due to the motor operating, the shaft and built-in magnet are also moved in the same direction.

        • When the shaft is moved to the left, causing the case to be moved in the same direction via the springs. Thus, the parking brake cable is pulled.

        • The springs compress in accordance with the tension acting on the parking brake cable, causing the positions of the case and magnet to change. As a result, the magnetic flux density changes. Hall ICs detect changes in the magnetic flux density, convert those changes into electrical signals, and then transmit them to the parking brake ECU assembly. Based on the signals received from Hall ICs, the parking brake ECU assembly calculates the tension of the parking brake cable.

          Figure 2. Parking Brake with Bracket Actuator Assembly Operation Image

          A01W77OC01
          *1 Equalizer *2 Parking Brake Cable
          *3 Case *4 Spring
          *5 Shaft *6 Hall IC
          *7 Magnet - -
      3. Electric Parking Brake Switch Assembly


        • When the driver pulls the manual switch, the parking brake becomes locked and pressing the manual switch releases the parking brake.

        • When the manual switch is pulled to the lock side at least 3 seconds while the vehicle stands still, the driver is notified through the multi-information display that the automatic function is now available.

        • When the vehicle is in a condition where no automatic function is available, the automatic function will never be turned on even if the manual switch is pulled to the lock side at least 3 seconds.

    7. Fail-safe


      1. When a malfunction has occurred in the system, the manual function maintains as much control as possible.

      2. When a malfunction has occurred in the system, the auto function bans control. In addition, control of the auto function is maintained while the electric parking brake switch assembly is malfunctioning.

      3. When malfunction has occurred with the parking brake locked, the locked parking brake can be released manually using the emergency release cable. For details, refer to the Repair Manual.

    8. Diagnosis


      1. If a malfunction is detected in the system, the parking brake ECU assembly will alert the driver by illuminating the brake system warning light (yellow indicator) in the combination meter and outputting a warning message on the multi-information display.

      2. At the same time, the Diagnosis Trouble Codes (DTCs) are stored in the memory. The DTCs stored in the parking brake ECU assembly are output to a Global TechStream (GTS) connected to the DLC3. For details, refer to the Repair Manual.