ELECTRONICALLY CONTROLLED BRAKE SYSTEM FAIL-SAFE CHART


  1. FAIL-SAFE FUNCTION OF CONTROL SYSTEM


    1. If a malfunction occurs in the skid control ECU assembly, sensor signal, or actuator, the remaining functioning components will maintain brake control.

    2. If a malfunction occurs in the brake control system, the skid control ECU assembly turns the warning light on, and prohibits ABS, BA VSC and brake hold operations.

      Item Operation
      Malfunction in the ABS

      ABS, BA, TRC and VSC control prohibited

      Brake hold control prohibited*
      Malfunction in the BA system

      ABS, BA, TRC and VSC control prohibited

      Brake hold control prohibited*
      Malfunction in the EBD system

      ABS, EBD, BA, TRC and VSC control prohibited

      Brake hold control prohibited*
      Malfunction in the TRC system

      ABS, BA, TRC and VSC control prohibited

      Brake hold control prohibited*
      Malfunction in the VSC system

      ABS, BA, TRC and VSC control prohibited

      Brake hold control prohibited*

      • *: Only during brake hold control

    3. A power back-up unit is built in as an additional power source to supply stable power to the system.

    4. The skid control ECU assembly prohibits VSC control in order to protect the system and prevent improper operation when related systems (hybrid control system, VGRS system, dynamic rear steering system) are malfunctioning.

    5. Brake hold control prohibits brake hold operation in order to protect the system and prevent improper operation when the electronically controlled brake system, electric parking brake system or hybrid control system is malfunctioning.

  2. FAIL-SAFE FUNCTION OF HYDRAULIC SYSTEM


    1. When a malfunction occurs, the skid control ECU prohibits operation of parts determined to be malfunctioning and continues brake power assist control using the properly functioning systems.

      Tech Tips


      • The system of wheels for which brake power assist is prohibited due to the fail-safe function loses brake power assist or braking ability.

      • If the brake power assist becomes prohibited, the feeling of the brake pedal may change.

      • If brake power assist becomes prohibited for all wheels, the 2 front wheels lose brake power assist.

    2. If the brake control is stopped under conditions such as when a malfunction occurs with a hydraulic pressure source, the pressure generated in the master cylinder by the driver is applied to the front wheel cylinders to ensure braking force.

    3. If the regenerative brake alone does not operate under conditions such as a communication error with the power management control ECU, control is switched so that all braking force is generated with hydraulic braking pressure.

      Item Operation
      Skid control ECU assembly malfunction Normally operating parts will control brake and generated braking force
      Hydraulic pressure controlling parts malfunction Normally operating parts will control brake and generated braking force
      Power supply parts (Hydraulic pressure source) malfunction Braking force solely generated by the driver