PRE-CRASH SAFETY SYSTEM SYSTEM DESCRIPTION


  1. PRE-CRASH SYSTEM


    1. The pre-crash system optimizes and activates occupant protection equipment (see below) to attempt to reduce damage due to a crash.

  2. OUTLINE OF PRE-CRASH SYSTEM

    Operating Condition Control Transmitting ECU Receiving ECU Part Operated
    Operates according to sensor detection Pre-crash seat belt Driving support ECU assembly Seat belt control ECU Front seat outer belts
    Operates according to sensor detection Pre-crash brake assist Driving support ECU assembly Brake booster with master cylinder (skid control ECU) Brake system
    Operates when sudden braking or sideways slippage occurs Pre-crash seat belt Brake booster with master cylinder (skid control ECU) Seat belt control ECU Front seat outer belts
    Operates according to sensor detection Pre-crash brake Driving support ECU assembly Brake booster with master cylinder (skid control ECU) Brake system

    1. When operating according to sensor detection:

      The millimeter wave radar sensor detects vehicles and other objects on the road in front of the user's vehicle. The Driving support ECU assembly determines if a crash is unavoidable based on object position, speed and track information. If the Driving support ECU assembly determines that a crash is unavoidable, it transmits this information to the following areas using CAN communication:


      • Seat belt control ECU (initiates control of pre-crash seat belts)

      • Brake booster with master cylinder (skid control ECU) (activates pre-crash brake assist system)

      • Brake booster with master cylinder (skid control ECU) (activates pre-crash brake)

    2. When operating as a result of sudden braking:

      The brake booster with master cylinder (skid control ECU) uses brake pressure information and other data to determine if the driver has suddenly applied the brakes. If so, the brake booster with master cylinder (skid control ECU) sends a signal to the seat belt control ECU through CAN communication and the pre-crash seat belts activate.

  3. OUTLINE OF PRE-CRASH SEAT BELT CONTROL


    1. The pre-crash seat belts operate depending on what the sensor detects, or whether sudden braking has occurred. The pre-crash seat belt motor retracts the seat belt to enhance pretensioner effectiveness.

    2. Operative condition


      1. Refer to the sensor and sudden braking descriptions under "Outline of Pre-Crash System" (see above).

  4. OUTLINE OF PRE-CRASH BRAKE ASSIST CONTROL


    1. The pre-crash brake assist operates depending on what the sensor detects. The system then enters standby mode before a crash. When the driver depresses the brake pedal, brake fluid pressure is increased to improve fluid pressure response and improve the rate of deceleration.

    2. Operative condition


      1. Refer to the sensor description under "Outline of Pre-Crash System" (see above).

      2. When the driver depresses the brake pedal after the driving support ECU assembly determines that a crash is unavoidable:

        Brake fluid pressure is increased at the same time the driver depresses the brake pedal.

  5. OUTLINE OF PRE-CRASH BRAKE CONTROL (w/ PRE-CRASH BRAKE)


    1. The pre-crash brake operates depending on what the sensor detects. This system can be canceled by the pre-crash brake cancel switch assembly.

      Tech Tips

      While the pre-crash brake is canceled, the PCS indicator light on the combination meter turns on.

    2. Operative condition


      1. Refer to the sensor description under "Outline of Pre-Crash System" (see above).

      2. When the driving support ECU assembly determines that a crash is unavoidable, the system performs brake control to reduce the vehicle speed.

  6. OPERATIVE CONDITION AND INOPERATIVE CONDITION OF EACH CONTROL (REVIEW)

    Tech Tips

    Each function will operate when all items marked (○) are satisfied.

    Pre-Crash Seat Belt*1 Pre-Crash Seat Belt*2 Pre-Crash Brake Assist*2 Pre-Crash Brake*2
    When power switch is on (IG) ○ ○ ○ ○

    No problem in related components ( Click here

    		○ ○ ○ ○
    When front seat belt(s) is/are fastened ○ ○ - -
    Operates when the vehicle speed is 30 km/h (19 mph) or more, regardless of relative speed ○ - - -
    Operates when the vehicle speed is 5 km/h (4 mph) or more and relative speed is 30 km/h (19 mph) or more - ○ - -
    Operates when the vehicle speed is 15 km/h (10 mph) or more and relative speed is 15 km/h (10 mph) or more - - - ○
    Operates when the vehicle speed is 30 km/h (19 mph) or more and relative speed is 30 km/h (19 mph) or more - - ○ -
    When pre-crash brake operation has not been disabled using the pre-crash brake cancel switch assembly - - - ○
    When the brake pedal is depressed - - ○ -

    • *1: Operates when sudden braking or skidding is detected.

    • *2: Does not operate in the following situations.


      • When the vehicle crashes with an object outside the detection range of the millimeter wave radar sensor assembly (side crash, rear crash, etc.)

      • When the millimeter wave radar sensor assembly cannot detect a possible crash object

    • ○: Main basis for operation

    • -: Not main basis for operation

  7. PRECAUTION FOR PRE-CRASH SYSTEM OPERATION


    1. When the millimeter wave radar sensor assembly detects an object in front of the vehicle under the conditions described below, the driving support ECU assembly may determine that a crash is unavoidable, and activate the pre-crash system. This activation of the system is not abnormal.

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      Tech Tips


      • The pre-crash system will not activate when approaching safety cones or other plastic objects as they cannot be detected by the pre-crash sensor.

      • The pre-crash system may or may not activate when the pre-crash sensor detects the following objects: people, bicycles, motorcycles, trees, animals and snow fences.

      • Detection performance may deteriorate in the following conditions.


        • On a tight curve or bumpy road

        • Something or someone suddenly emerges in the direction of travel of the driver's vehicle at a place such as an intersection

        • Another vehicle suddenly cuts in traveling direction of driver's own vehicle

        • In severe weather such as heavy rain, fog , snow or a sand storm

        • Vehicle is skidding sideways while electronically controlled brake system is not operating

        • Vehicle height changes significantly (front of vehicle inclined either upward or downward)

        • Millimeter wave radar sensor assembly is misaligned (due to reinstallation or crash)

          Object Type Example
          Objects that cannot be detected Plastic items (safety cones)
          Objects that cannot be detected in a stable manner People, bicycles, motorcycles, trees, animals, snow fences, etc.