ELECTRIC PARKING BRAKE SYSTEM


  1. FUNCTION OF MAIN COMPONENTS

    Component Function
    Parking Brake 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

    • Locks the parking brake when the switch is pushed, and releases the parking brake when the switch is pulled.

    • Switches the auto function on and off.
    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 cannot be operated by driver switch operations or that a locked cable may have become loose due to external factors.
    Brake Warning Light / Yellow (Minor Malfunction) Lights up to inform the driver that the electric 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 electric parking brake ECU assembly has a malfunction in the system.
    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.
    Yawrate Sensor Deceleration Sensor Detects the gradient of the road surface by detecting the inclination of the vehicle.
    Parking Brake ECU Assembly Controls the motor in the parking brake actuator assembly based on operation signals from the electric parking brake switch assembly and parking brake request signals from ECUs.
    Hybrid Vehicle Control ECU Assembly Sends the accelerator pedal position signal and shift position signal to the parking brake ECU assembly.
    Skid Control ECU Assembly

    • Sends the wheel speed signal, brake master cylinder pressure signal and brake pedal depressed signal to the parking brake ECU assembly.

    • Sends the parking brake lock request signal to the parking brake ECU assembly.
    Airbag ECU Assembly Sends the driver seat belt fasten condition signal to the main body ECU (multiplex network body ECU).
    Main Body ECU (Multiplex Network Body ECU) Sends the driver side door opening or closing state signal and driver seat belt fasten condition signal to the parking brake ECU assembly.
    Central Gateway ECU (Network Gateway ECU) Relays and transmits each CAN communication data signal.

  2. SYSTEM CONTROL


    1. The parking brake ECU assembly 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 parking brake ECU assembly detects the motor operation condition via its built-in current sensor and signals from the tension sensor built-into the parking brake actuator assembly.

    3. The parking brake ECU assembly generates braking force according to the road surface while the vehicle is stopped by calculating the road grade based on the signal from the deceleration sensor to control the motor drive current.

  3. FUNCTION


    1. Manual Function


      1. When the electric parking brake switch assembly is pushed with the vehicle stopped, the parking brake locks.

      2. When the electric parking brake switch assembly is pulled, the parking brake releases.

      3. The motor in the parking brake actuator assembly operates to generate braking force only while the electric parking brake switch is pushed when the vehicle is in motion. When the electric parking brake switch is released, the motor in the parking brake actuator assembly operates in reverse to decrease the braking force.

      4. The parking brake lock operation can be operated regardless of whether the power switch is turned on (IG) or off.

      5. The parking brake can be released when the power switch is turned on (IG).

    2. Auto Function


      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 pushed and held for 3 seconds or more with the parking brake locked, the auto function turns on. Then a piece of information is displayed on the multi-information display indicating that the auto function is on.

        Tech Tips

        When switching from the parking brake released condition, it is necessary to press it for 5 seconds or more.

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

        Tech Tips

        When switching from the parking brake locked condition, it is necessary to pull it for 5 seconds or more.

      4. When the driver changes the shift position to P while the auto function is on, the parking brake is locked. Also, when the shift position is changed from P to any other position with the brake pedal depressed, the parking brake is released.

    3. Parking Brake Automatic Release Function


      1. When all of the following conditions are met and the driver depresses the accelerator pedal, the parking brake is released.


        • Driver side door is closed.

        • Shift position is not in P or N.

        • Driver side seat belt is fastened.

  4. FAIL-SAFE


    1. When a malfunction occurs in the system, control using the manual function is maintained as much as possible and control using the auto function and parking brake automatic release function is prohibited.

      Tech Tips

      When a malfunction occurs in the electric parking brake switch assembly, the system automatically switches to the auto function to ensure operability.

    2. 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.

    3. When the parking brake cannot be released due to a mechanical malfunction, the parking brake can be released by using the emergency release cable. For details, refer to the Repair Manual.

  5. DIAGNOSIS


    1. If a malfunction is detected in the system, the parking brake ECU assembly 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 parking brake ECU assembly are output to the Global TechStream (GTS) connected to the DLC3. For details, refer to the Repair Manual.