ELECTRIC PARKING BRAKE SYSTEM


  1. FUNCTION OF MAIN COMPONENTS

    Component Function
    Rear Disc Brake Caliper Assembly Parking Brake Actuator Assembly Controls the brake pad position by operating the motor according to signals from the skid control ECU and locks or releases the parking brake.
    Electric Parking Brake Switch Assembly Electric Parking Brake Switch

    • Sends the lock or release operation signal to the skid control ECU.

    • 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 Warning Light Each light illuminates, blinks, as well indicates on the multi-information display, to inform the driver of the system control conditions.
    Brake Warning Light / Yellow (Minor Malfunction)
    Brake Warning Light / Red (Malfunction)
    Auto P-off Indicator Light*
    Multi-information Display
    Master Warning Light
    Buzzer
    Airbag Sensor Assembly Yawrate Sensor Detects the gradient of the road surface by detecting the inclination of the vehicle.
    Acceleration Sensor
    Network Gateway ECU Relays data between buses.
    ECM Transmits the shift lever position to the skid control ECU.
    Brake Actuator Assembly Skid Control ECU

    • Detects the speed sensor and master cylinder pressure sensor signals.

    • Controls the motor in the parking brake actuator assembly based on information from the electric parking brake switch, the built-in current sensor and each ECU.

    *: Models with manual transaxle

  2. SYSTEM CONTROL


    1. The skid control ECU locks or releases the parking brake by controlling the rotation direction and drive current of the motor built into the parking brake actuator assembly based on signals from the electric parking brake switch and each ECU.

    2. The skid control ECU detects the operation condition of the motor via the built-in current sensor.

  3. FUNCTION


    1. Manual Function


      1. When the electric parking brake switch is pulled with the vehicle stopped, the skid control ECU operates the motor in the parking brake actuator assembly to lock the parking brake. At this time, the skid control ECU generates braking force according to the road surface by calculating the road grade based on the signal from the acceleration sensor and controlling the motor drive current.

      2. When the brake pedal is depressed, and then the electric parking brake switch is pushed, the skid control ECU operates the motor in the parking brake actuator assembly in reverse to release the parking brake.

      3. The brake fluid pressure in the brake actuator assembly is used to generate braking force only while the electric parking brake switch is pulled when the vehicle is in motion. When the electric parking brake switch is released, the brake fluid pressure in the brake actuator assembly is released to decrease the braking force.

      4. The parking brake lock operation can be operated regardless of whether the ignition switch is turned ON or off.

      5. The parking brake can be released when the ignition switch is turned ON.

      6. When a malfunction occurs with the electric parking brake switch, the auto function automatically turns on.

    2. Auto Function (Models with CVT)


      1. The manual function can be switched to the auto function via operation of the electric parking brake switch.

      2. When the electric parking brake switch is pulled and held for 5 seconds or more with the parking brake locked, the auto function turns on. Then a warning is displayed on the multi-information display indicating that the auto function is on.

      3. When the electric parking brake switch is pushed and held for 5 seconds or more with the parking brake released, the auto function turns off. Then a warning is displayed on the multi-information display indicating that the auto function is off.

      4. When the driver moves the shift lever from a position other than P to P with the auto function on, the skid control ECU operates the motor in the parking brake actuator assembly to lock the parking brake. Also, when the shift lever is moved from P to a position other than P with the brake pedal depressed, the parking brake is released.

    3. Auto Function (Models with Manual Transaxle)


      1. The manual function can be switched to the auto function via operation of the electric parking brake switch.

      2. When the electric parking brake switch is pulled and held for 5 seconds or more with the parking brake locked, the auto function turns on. Then the auto P-off indicator light turns off to indicate that the auto function is on.

      3. When the electric parking brake switch is pushed and held for 5 seconds or more with the parking brake released, the auto function turns off. Then the auto P-off indicator light turns on to indicate that the auto function is off.

      4. When the auto function is on, if the driver turns the ignition switch off, the skid control ECU controls the parking brake actuator assembly motor operation and locks the parking brake.

    4. Backup Function


      1. The electric parking brake system automatically operates the motor in the parking brake actuator assembly to maintain the vehicle parked position in the following conditions.


        • When a malfunction occurs in the brake hold function while the vehicle is stopped via operation of the brake hold function.

        • When a brake operation is not performed for 3 minutes while the vehicle is stopped via operation of the brake hold function.

        • When a malfunction occurs in the brake hold function while the dynamic radar cruise control system holds the vehicle parked position (brake hold function operating).*

        *: Models with Toyota Safety Sense

  4. 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 and backup function prohibits control.

      Tech Tips

      When a malfunction occurs with the electric parking brake switch, parking brake control via the auto function is maintained.

    3. When the parking brake cannot be released due to the fail-safe state or a malfunction in the power source system, the parking brake can be released by supplying power to the electric release connector. For details, refer to the Repair Manual.

    4. When the parking brake cannot be released due to a mechanical malfunction, the parking brake can be released by removing the parking brake actuator assembly from the brake caliper. For details, refer to the Repair Manual.

  5. DIAGNOSIS


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

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