AIRBAG SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components in the airbag system have the following functions:

      Component Function
      Airbag Sensor Assembly

      • In the event of a frontal collision, the airbag sensor assembly receives signals from either of the front airbag sensors. The airbag sensor assembly receives the signal via its judgment circuit and also receives another signal from the safing sensor built into the airbag sensor assembly. After receiving a signal from at least one of the front airbag sensors and the safing sensor, the airbag sensor assembly determines whether the driver airbag, front passenger airbag*1, driver knee airbag*2, curtain shield airbags*3, front seat airbags*3 and seat belt pretensioners should be deployed. The airbag sensor assembly also diagnoses system malfunctions.

      • In the event of a side or rear side collision, the airbag sensor assembly receives signals from the side airbag sensor assembly*4, front floor side airbag sensor*5 or door side airbag sensor assembly. The airbag sensor assembly receives the signal via its judgment circuit and also receives another signal from the safing sensor built into the airbag sensor assembly. After receiving a signal from the side*4 or door side airbag sensors, front floor side airbag sensor*5 and the safing sensor, the airbag sensor assembly determines whether the seat airbag assemblies and curtain shield airbag assemblies should be deployed. The airbag sensor assembly also diagnoses system malfunctions.*3

      • The airbag sensor assembly sends an airbag deployment signal to the ECM through the Controller Area Network (CAN) to operate fuel pump control.
      Horn Button Assembly The airbags are used as supplements to the seat belts to help reduce impact to the occupants.
      Instrument Panel Passenger Airbag without Door Assembly*1
      No. 1 Lower Instrument Panel Airbag Assembly*2
      Front Seat Airbag Assembly LH/RH*3
      Curtain Shield Airbag Assembly LH/RH*3
      Front Airbag Sensor LH/RH Based on the deceleration of the vehicle during a frontal collision, distortion is created in the sensor and converted into an electrical signal.
      Side Airbag Sensor Assembly LH/RH*3, *4 Based on the deceleration of the vehicle during a side or rear side collision, distortion is created in the sensor and converted into an electrical signal.
      Door Side Airbag Sensor LH/RH*3
      Front Floor Side Airbag Sensor LH/RH*5
      Front Seat Outer Belt Assembly LH/RH The front seat outer belt assemblies are used to help reduce impact to the occupants.
      Rear No. 1 Seat Outer Belt Assembly LH/RH*6 The rear No. 1 seat outer belt assemblies are used to help reduce impact to the occupants.
      Combination Meter Assembly SRS Airbag Warning Light Turns on to alert the driver when the airbag sensor assembly detects a malfunction in the airbag system.
      Occupant Detection ECU*7 The occupant detection ECU judges whether the front passenger seat is occupied.
      Central Gateway ECU*8 Transmits the signal between the CAN communication buses.

      • *1: Models with SRS front passenger airbag

      • *2: Models with SRS driver knee airbag

      • *3: Models with SRS front side airbag and SRS curtain shield airbag

      • *4: Smart cab models or double cab models

      • *5: Models with driver dual-stage SRS airbag

      • *6: Models with rear pretensioner squib

      • *7: Models with occupant classification system

      • *8: Models with central gateway ECU

  2. SYSTEM CONTROL


    1. Airbag for Frontal Collision


      1. There are 7 airbags which deploy in the event of a frontal collision: the horn button assembly, instrument panel passenger airbag without door assembly*1, No. 1 lower instrument panel airbag assembly*2, front seat airbag assemblies*3 and curtain shield airbag assemblies*3. These airbags deploy simultaneously. In addition, the front or rear pretensioners contained in the front seat outer belt assembly LH/RH and rear No. 1 seat outer belt assembly LH/RH*4 are also activated.

      2. For a frontal collision, if a front airbag sensor detects an impact, it informs the airbag sensor assembly. The airbag sensor assembly causes the horn button assembly, instrument panel passenger airbag without door assembly*1, No. 1 Lower instrument panel airbag assembly*2, front seat airbag assemblies*3 and curtain shield airbag assemblies*3 to deploy. Meanwhile, the airbag sensor assembly activates the seat belt pretensioners for the driver, front passengers and rear passengers*4.


        • *1: Models with SRS front passenger airbag

        • *2: Models with SRS driver knee airbag

        • *3: Models with SRS front side airbag and SRS curtain shield airbag

        • *4: Models with rear pretensioner squib

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      3. Deceleration sensors used for the airbag system are installed on various parts on the vehicle and calculate the deceleration (or acceleration) rate of each part during a collision.

      4. Depending on the situation, the airbag sensor assembly sends a deployment signal to each airbag based on the information from each sensor.

      5. Frontal collision signals are produced based on the information from the airbag sensor assembly and front airbag sensors. Frontal collision signals are used to deploy the airbags and activate the pretensioners as indicated in the table below.

        Figure 1. Frontal Collision

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    2. Airbag for Side/Rear Side Collision (Models with SRS Curtain Shield Airbag and SRS Side Airbag)


      1. There are 2 airbags which deploy in the event of a severe side collision: the front seat airbag assembly and curtain shield airbag assembly. These airbags deploy simultaneously.

      2. For a side collision, if the side airbag sensor assembly and front floor side airbag sensor*1 detect an impact, they inform the airbag sensor assembly, and the airbag sensor assembly causes the front seat airbag assembly and curtain shield airbag assembly to deploy simultaneously. Meanwhile, the airbag sensor assembly activates the front seat belt pretensioner and rear seat belt pretensioner*2.


        • *1: Models with driver dual-stage SRS airbag

        • *2: Models with rear pretensioner squib

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      3. The front seat airbag assembly and curtain shield airbag assembly are deployed based on signals from the door side airbag sensor, front floor side airbag sensor* and airbag sensor assembly.


        • *: Models with driver dual-stage SRS airbag

        Figure 2. Side Collision

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      4. For a rear side collision, if the side airbag sensor assembly and front floor side airbag sensor*1 detect an impact, they inform the airbag sensor assembly, and the airbag sensor assembly causes the curtain shield airbag assembly to deploy simultaneously. Meanwhile, the airbag sensor assembly activates the rear seat belt pretensioner*2.*3


        • *1: Models with driver dual-stage SRS airbag

        • *2: Models with rear pretensioner squib

        • *3: Smart cab models or double cab models

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      5. The curtain shield airbag assembly is deployed based on signals from the door side airbag sensor assemblies or the side airbag sensor assemblies and the airbag sensor assembly.

        Figure 3. Rear Side Collision (Smart Cab Models or Double Cab Models)

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    3. Primary Check Illumination Control


      1. After the ignition switch is turned to ON, the airbag sensor assembly illuminates the SRS airbag warning light in the combination meter assembly for approximately 6 seconds and conducts the primary check. During the primary check, the ignition of airbags is prohibited and a diagnosis of the airbag sensor assembly is performed. If a malfunction is detected during the primary check, the SRS airbag warning light remains on even after the 6 seconds have elapsed.

      2. After the ignition switch is turned to ON, the airbag sensor assembly operates the passenger AIRBAG ON/OFF indicator lights as shown below to check for an open in the indicator light circuits.

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  3. FUNCTION


    1. Airbag Cut Off Switch Cylinder Sub-assembly (Models with Airbag Cut Off Switch Cylinder Sub-assembly)


      1. A cylinder to disable the deployment of the instrument panel passenger airbag without door assembly and the front seat airbag assembly*1 has been provided. This cylinder can be used if the deployment of those airbags is dangerous, such as when the passenger is wearing a Child Restraint System (CRS) seat belt.

      2. This cylinder is located on the front passenger side of the instrument panel. The airbag cut off switch cylinder sub-assembly is switched on or off using an ignition key*2 or mechanical key*3. When the airbag cut off switch cylinder sub-assembly is off, the passenger AIRBAG OFF indicator light illuminates. At this time, the instrument panel passenger airbag without door assembly and the front seat airbag assembly*1 will be disabled regardless of the collision conditions.


        • *1: For passenger side

        • *2: Models without entry and start system

        • *3: Models with entry and start system

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        *1 AIRBAG OFF Indicator Light *2 AIRBAG ON Indicator Light
        *3 Airbag Cut Off Switch Cylinder Sub-assembly - -

  4. DIAGNOSIS


    1. If the airbag sensor assembly detects a malfunction in the SRS airbag system, the airbag sensor assembly stores the malfunction data in memory in addition to illuminating the SRS airbag warning light.

    2. The airbag sensor assembly outputs malfunction data and 5-digit Diagnostic Trouble Codes (DTCs) to the Global TechStream (GTS).

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

    4. If the SRS airbags deploy, the airbag sensor assembly will turn on the SRS airbag warning light. However, unlike the ordinary diagnosis function, a DTC will not be stored. The SRS airbag warning light cannot be manually turned off. It is necessary to replace the airbag sensor assembly with a new one.