OCCUPANT CLASSIFICATION SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components in 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 the front passenger seat belt buckle switch.
      Airbag ECU Assembly

      • Receives the signals of the result of the judgment from the occupant detection ECU, and restricts the deployment of the SRS front passenger airbag and SRS front passenger knee airbag.

      • Outputs the illumination signals to the AIRBAG ON/OFF indicator lights.
      Front Occupant Classification Sensor The output values of this sensor, which vary in accordance with the distortion that acts on the brackets, are output to the occupant detection ECU.
      Rear Occupant Classification Sensor
      Front Passenger Seat Belt Buckle Switch (Front Seat Inner Belt Assembly RH) Detects if the front passenger seat belt is fastened.
      Telltale Light Assembly

      AIRBAG ON

      Indicator Light

      		 Turns on to inform the driver when the occupant detection ECU has put the SRS front passenger airbag and SRS front passenger knee airbag into an active state.

      AIRBAG OFF

      Indicator Light

      • Turns on to inform the driver when the occupant detection ECU has put the SRS front passenger airbag and SRS front passenger knee airbag into an inactive state.

      • Turns on to alert the driver when the airbag ECU assembly detects a malfunction in the occupant classification system.
      Combination Meter Assembly SRS Warning Indicator Turns on to alert the driver when the airbag ECU assembly detects a malfunction in the SRS airbag system.
      Central Gateway ECU (Network Gateway ECU) Relays the signal between the CAN communication lines.
      DLC3 The Global TechStream (GTS) can be connected to read the Diagnostic Trouble Codes (DTCs) of malfunctions.

  2. OPERATING CONDITION


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

      Item Occupant Classification
      Adult*1 Child*2 Child Seat Unoccupied Malfunction
      Front Passenger Airbag ○ X X X X
      Front Passenger Knee Airbag ○ X X X X
      Front Passenger Side Airbag ○ ○ ○ ○ ○
      Curtain Shield Airbag Assembly RH ○ ○ ○ ○ ○
      Front Passenger Seat Belt Pretensioner ○ ○ ○ ○ ○
      ON Indicator Light Illuminates - - - -
      OFF Indicator Light - Illuminates Illuminates Illuminates Illuminates

      Tech Tips

      ○ : Enabled

      X : Disabled

      *1: The system judges a person of average adult weight or more as an adult. If a smaller adult sits in the front passenger seat, the system may not recognize them as an adult depending on their physique and posture.

      *2: The system may not recognize a child or a child in a child restrain system as a child depending on factors such as the positioning of the child restraint system or the child's physique or posture.

  3. 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, 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 criteria value "B", and disables the SRS front passenger airbag and SRS front passenger knee airbag.

    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 is off.

      2. If the engine switch is turned on (IG) in this state, the system performs an initial check, and illuminates the AIRBAG OFF indicator light. Then, the system prohibits the deployment of the SRS front passenger airbag and SRS front passenger knee airbag, and does not blink the seat belt warning indicator.

        B0056CAE02

    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 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 is off, the occupant detection ECU judges that the seat is being occupied by a child.

      3. When the engine 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 SRS front passenger airbag and SRS front passenger knee airbag have been deactivated.

        B0056R7E01

    4. Adult Judgment


      1. 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 is turned off.

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

      3. If the engine switch is turned on (IG) in this state, the system performs an initial check and illuminates the AIRBAG ON indicator light, indicating that the SRS front passenger airbag and SRS front passenger knee airbag are active.

        B0056DCE01

    5. After the engine switch is turned to on (IG), the occupant detection ECU illuminates the AIRBAG ON/OFF indicator lights via the airbag ECU assembly based on the timing chart below in order to check the indicator light circuits:

      B0056JEE02

  4. 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. If the airbag ECU assembly detects a malfunction in the occupant detection ECU, the airbag ECU assembly illuminates the SRS warning light and AIRBAG OFF indicator light.

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

    3. The 5-digit DTCs can be read by connecting the Global TechStream (GTS) to the DLC3. For details, refer to the Repair Manual.