OCCUPANT CLASSIFICATION SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components of the occupant classification system have the following functions:

      Component Function
      Occupant Detection ECU Judges whether the front passenger seat is occupied based on signals from 2 occupant classification sensors and front passenger seat belt buckle switch (front seat inner belt assembly RH).
      Airbag Sensor Assembly

      • Receives the signals of the result of the judgment from occupant detection ECU, restricts the activation of the SRS front passenger airbag, SRS front seat cushion airbag for front passenger, SRS side airbag for front passenger, seat belt pretensioner for front passenger and selectable force limiter for front passenger.

      • Outputs the illumination signals to the AIRBAG ON/OFF indicator lights.
      Front Occupant Classification Sensor LH The sensors are strain gauge type sensors that send signals to the occupant detection ECU in accordance with the weight of the occupant.
      Rear Occupant Classification Sensor LH
      Front Passenger Seat Belt Buckle Switch (Front Seat Inner Belt Assembly RH) Detects if the front passenger seat belt is fastened.
      Combination Meter Assembly SRS Warning Light Turns on to alert the driver when the airbag sensor assembly detects a malfunction in the occupant classification system.
      Multi-information Display Displays a warning message to inform the driver of a malfunction in the occupant classification system.
      Master Warning Light Turns on to alert the driver when the airbag sensor assembly detects a malfunction in the occupant classification system.
      Buzzer Sounds to warn the driver of a malfunction in the occupant classification system.
      Seat Belt Warning Light Indicates the state of the front seat belts.
      Radio Receiver Assembly AIRBAG OFF Indicator Light

      • Informs the driver whether the occupant detection ECU has put the instrument panel passenger airbag without door assembly, front seat cushion airbag assembly RH, front seat airbag assembly RH and front seat outer belt assembly RH into an active state or inactive state.

      • If a malfunction occurs in the occupant classification system, the AIRBAG OFF indicator light comes on.
      AIRBAG ON Indicator Light
      Network Gateway ECU Relays the signal between the CAN communication.

  2. SYSTEM CONTROL


    1. Summary


      1. In the occupant classification system, the occupant detection ECU calculates the weight of the occupant based on signals from the occupant classification sensors.

      2. The occupant detection ECU contains criteria value "A" to judge whether the seat is occupied by a child or is unoccupied in accordance with the signals from the 2 occupant classification sensors and front passenger seat belt buckle switch (front seat inner belt assembly RH), and criteria value "B" to judge whether the occupant is an adult or child (with child seat).

      3. This system recognizes the occupant as a child or child seat if it detects a weight of less than "B", and disables the instrument panel passenger airbag without door assembly, front seat cushion airbag assembly RH and front seat airbag assembly RH.

    2. Unoccupied Judgment


      1. The occupant detection ECU makes an unoccupied judgment when the judgment value is lower than criteria value "A" and the front passenger seat belt buckle switch (front seat inner belt assembly RH) is off.

      2. If the power switch is turned on (IG) in this state, the system performs an initial check. Then, the system prohibits the deployment of the instrument panel passenger airbag without door assembly, front seat cushion airbag assembly RH and front seat airbag assembly RH, prohibits the activation of the front seat outer belt assembly RH and does not blink the seat belt warning light.

        B0055GKE01

    3. Child Seat or Child Judgment


      1. If the judgment value is lower than criteria value "B" and the front passenger seat belt buckle switch (front seat inner belt assembly RH) is ON, the occupant detection ECU judges that a child seat is installed.

      2. If the judgment value is higher than criteria value "A", but lower than criteria value "B", and the front passenger seat belt buckle switch (front seat inner belt assembly RH) is OFF, the occupant detection ECU judges that the seat is being occupied by a child.

      3. When the power switch is turned on (IG) under these conditions, the system performs an initial check and illuminates the AIRBAG OFF indicator light to indicate that the instrument panel passenger airbag without door assembly, front seat cushion airbag assembly RH and front seat airbag assembly RH have been deactivated.

        B0055K3E01

      4. After the occupant detection ECU judges that a child seat is installed, the AIRBAG OFF indicator light does not go off unless the front passenger seat belt buckle switch (front seat inner belt assembly RH) is turned OFF.

    4. Adult Judgment


      1. When the judgment value is higher than criteria value "B", the occupant detection ECU judges that the seat is occupied by an adult.

      2. If the power switch is turned on (IG) in this state, the system performs an initial check and illuminates the AIRBAG ON indicator light, indicating that the instrument panel passenger airbag without door assembly, front seat cushion airbag assembly RH, front seat airbag assembly RH and front seat outer belt assembly RH are active.

        Tech Tips

        The front seat cushion airbag assembly RH cannot be deployed when the front passenger seat belt has been unfastened.

        B0055OQE01

      3. After the occupant detection ECU judges that the occupant is an adult, and if the judgment value is determined as criteria value "A" or less according to occupant load movement and the front passenger seat belt buckle switch (front seat inner belt assembly RH) is off, the ECU continues adult judgment for approximately 20 seconds before switching to the unoccupied judgment.

    5. Primary Check Illumination Control


      1. After the power switch is turned on (IG), the occupant detection ECU operates the AIRBAG ON/OFF indicator lights via airbag sensor assembly as shown below to check for an open in the indicator light circuits.

        B0055BME40

    6. The front passenger SRS items and indicator lights operate as follows according to the occupant classification:

      Items Occupant Classification
      Adult Child Child Seat Unoccupied Malfunction
      Front Passenger SRS Components Front Airbag ○ X X X X
      Seat Cushion Airbag ○* X X X X
      Side Airbag ○ X X X X
      Seat Belt Pretensioner ○ ○ ○ X ○
      Selectable Force Limiter ○ ○ ○ X ○
      AIRBAG ON/OFF Indicator Lights AIRBAG ON Indicator Light ON OFF OFF OFF OFF
      AIRBAG OFF Indicator Light OFF ON ON OFF ON

      ○: Deploys or activates

      X: Does not deploy or activate

      *: Cannot be deployed when the front passenger seat belt has been unfastened.

  3. DIAGNOSIS


    1. If the occupant detection ECU detects a malfunction in the occupant classification system, the occupant detection ECU stores the malfunction data in memory as Diagnostic Trouble Codes (DTCs). If the airbag sensor assembly detects a malfunction in the occupant classification system via the occupant detection ECU, the airbag sensor assembly illuminates the AIRBAG OFF indicator light, SRS warning light and master warning light, displays the warning message on the multi-information display and sounds the buzzer to alert the driver of the malfunction.

    2. The occupant detection ECU outputs 5-digit Diagnostic Trouble Codes (DTCs) to the Techstream.

    3. The 5-digit DTCs can be read by connecting the Techstream to the DLC3. For details, refer to the Repair Manual.