AIRBAG SYSTEM DETAILS


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components have the following functions:

      Component Function
      Airbag Sensor Assembly
      • The airbag sensor assembly receives signals from one of the front airbag sensors via its judgment circuit and from the safing sensor built into the airbag sensor assembly. After receiving these signals, it determines whether the driver airbag, front passenger airbag, driver knee airbag*1, curtain shield airbag, and front seat belt pretensioners should be activated. It also diagnoses system malfunctions.

      • The airbag sensor assembly receives signals from either the side airbag sensor assembly or No. 2 side airbag sensor assembly via its judgment circuit and from the safing sensor built into the airbag sensor assembly. After receiving these signals, it determines whether the front seat airbag assembly, rear seat airbag assembly*2, curtain shield airbag and front seat belt pretensioner should be activated. It also diagnoses system malfunctions.

      • The airbag sensor assembly sends an airbag deployment signal to the ECM through the Controller Area Network (CAN) to operate fuel pump control.

      • The airbag sensor assembly sends an airbag deployment signal to the main body ECU (multiplex network body ECU) through the direct line to operate the collision door lock release function.

      Horn Button Assembly Driver Side Squib The airbags are used as supplements to the seat belts to help reduce impact to the occupants.
      Instrument Panel Passenger Airbag without Door Assembly Front Passenger Side Squib
      Lower No. 1 Instrument Panel Airbag Assembly*1 Driver Knee Airbag Squib
      Front Seat Airbag Assembly LH/RH Front Side Airbag Squib LH/RH
      Rear Seat Airbag Assembly LH/RH*2 Rear Side Airbag Squib LH/RH
      Curtain Shield Airbag Assembly LH/RH Curtain Shield Squib LH/RH
      Front Airbag Sensor LH/RH Based on the deceleration of the vehicle during a frontal collision, a distortion is created in the sensor and converted into an electrical signal. Accordingly, the extent of the initial collision can be detected in detail.
      Side Airbag Sensor Assembly LH/RH Based on the deceleration of the vehicle during a side or side rear collision, a distortion is created in the sensor and converted into an electrical signal.
      No. 2 Side Airbag Sensor assembly LH/RH
      Front Seat Outer Belt Assembly LH/RH Front Pretensioner Squib LH/RH The front seat outer belt assemblies are used to help reduce impact to the occupants.
      Combination Meter Assembly SRS Warning Light The SRS warning light turns on to alert the driver when the airbag sensor assembly detects a malfunction in the airbag system.

      *1: Models with SRS driver knee airbag

      *2: Models with SRS rear side airbags

  2. OPERATING CONDITION


    1. Ignition Condition


      1. 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.

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

      3. 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 except the side airbags.

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      4. The front seat airbag assemblies are deployed and the front seat outer belt assemblies are activated based on signals from the side airbag sensor assemblies and airbag sensor assembly.

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      5. The rear seat airbag assemblies and curtain shield airbag assemblies are deployed based on signals from the No. 2 side airbag sensor assemblies or the side airbag sensor assemblies and the airbag sensor assembly.

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  3. SYSTEM CONTROL


    1. Airbag for Frontal Collision


      1. There are 5 airbags which deploy in the event of a frontal collision: the horn button assembly, instrument panel passenger airbag without door assembly, lower No. 1 instrument panel airbag assembly*.

        *: Models with SRS driver knee airbag

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    2. Airbag for Side/Side Rear Collision


      1. There are 3 airbags which deploy in the event of a severe side collision: the front seat airbag assembly, rear seat airbag assembly* and curtain shield airbag assembly. These airbags deploy simultaneously. Additionally, at the same time, the front seat outer belt assembly is also activated.

      2. For a side collision, if the side airbag sensor assembly detects an impact, it informs the airbag sensor assembly, and the airbag sensor assembly causes the front seat airbag assembly, rear seat airbag assembly* and curtain shield airbag assembly to deploy simultaneously, and activates the front seat outer belt assembly.

        *: Models with SRS rear side airbags

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      3. For a side rear collision, if the No. 2 side airbag sensor assembly detects an impact, it informs the airbag sensor assembly via the side airbag sensor assembly, and the airbag sensor assembly causes the curtain shield airbag assembly and rear seat airbag assembly* to be deployed.

        *: Models with SRS rear side airbags

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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 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 trouble is detected during the primary check, the SRS warning light remains on even after the 6 seconds have elapsed.

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  4. CONSTRUCTION


    1. Airbag Sensor Assembly


      1. The airbag sensor assembly consists of judgment circuits, a safing sensor, ignition control circuit, backup power source, diagnostic circuit and memory circuit.

        Item Outline
        Judgment Circuit Judgment circuits are built into the airbag sensor assembly to judge the severity of a collision using the acceleration/deceleration signals from the front airbag sensors, side airbag sensors and No. 2 side airbag sensors.
        Deceleration Sensor A deceleration sensor is built into the airbag sensor assembly. This sensor distorts in the event of a collision. The amount of distortion is based on the deceleration rate of the vehicle during a frontal collision and is converted into an electric signal.
        Ignition Control Circuit The ignition control circuit performs calculations based on the signal output from the judgment circuit of the airbag sensor assembly, front airbag sensors, side airbag sensor assemblies and No. 2 side airbag sensor assemblies. If the calculated values are greater than the specified values, the airbags are deployed.
        Safing Sensor During a frontal, side or side rear collision, this sensor turns on and outputs an on signal to the airbag sensor assembly if the deceleration rate of the safing sensor is greater than a specified value.
        Backup Power Circuit The backup power circuit consists of a power supply capacitor and a DC-DC converter. When the power supply to the airbag sensor assembly is disrupted during a collision, the power supply capacitor discharges and supplies electric power to the system. The DC-DC converter operates as a boosting transformer when the battery voltage falls below a predetermined level.
        Diagnostic Circuit The diagnostic circuit constantly monitors for system malfunctions. When a malfunction is detected, it turns on the SRS warning light in the combination meter assembly to inform the driver.
        Memory Circuit When a malfunction is detected by the diagnostic circuit, a DTC is stored in memory.
    2. Horn Button Assembly


      1. The horn button assembly contains an initiator and propellant.

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        Text in Illustration
        *1 Bag *2 Inflator
        *3 Initiator Connector - -
        *a A-A Cross Section *b Reverse Side
    3. Instrument Panel Passenger Airbag without Door Assembly


      1. The instrument panel passenger airbag without door assembly contains an initiator and propellant.

      2. When the instrument panel passenger airbag without door assembly is deployed, it forms the shapes of 2 bags with a depression in the middle. Immediately after the airbag is deployed, the shapes of 2 bags support the occupant on many planes, including the head and shoulders. Thus, this airbag disperses the load that is applied to the occupant in order to lessen the localized impact that is applied to the occupant immediately upon deployment.

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        Text in Illustration
        *1 Initiator Connector *2 Inflator
        *3 Bag *4 Depression
        *a A-A Cross Section - -
    4. Lower No. 1 Instrument Panel Airbag Assembly


      1. The knee airbag assembly consists of an airbag door, inflator and a bag.

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        Text in Illustration
        *1 Inflator *2 Bag
        *a A-A Cross Section - -
    5. Front Seat Airbag Assembly


      1. Each front seat airbag assembly is a one-piece design, consisting of an inflator and a bag.

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        Text in Illustration
        *1 Front Seat Airbag Assembly *2 Inflator
        *3 Bag - -
        *a A-A Cross Section *b B-B Cross Section
    6. Rear Seat Airbag Assembly


      1. Each rear seat airbag assembly is a one-piece design, consisting of an inflator and a bag.

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        Text in Illustration
        *1 Rear Seat Airbag Assembly *2 Inflator
        *3 Bag - -
        *a A-A Cross Section *b B-B Cross Section
    7. Curtain Shield Airbag Assembly


      1. Each curtain shield airbag assembly is a one-piece design, consisting of an inflator and a bag.

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        Text in Illustration
        *1 Curtain Shield Airbag Assembly *2 Inflator
        *3 Bag - -
        *a A-A Cross Section - -
    8. Front Airbag Sensor


      1. The front airbag sensors are electrical type deceleration sensors. As a result of the deceleration of the vehicle during a frontal collision, a distortion is created in the internal element in the sensor and converted into an electrical signal. Accordingly, the extent of the initial collision can be detected in detail.

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    9. Side Airbag Sensor Assembly and No. 2 Side Airbag Sensor Assembly


      1. A deceleration sensor is enclosed in the side airbag sensor assembly and No. 2 side airbag sensor assembly. As a result of the deceleration of the vehicle during a side or side rear collision, a distortion is created in the internal element in the sensor and converted into an electrical signal.

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  5. 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 warning light.

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

    3. The 5-digit DTCs can be read after connecting the intelligent tester 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 warning light. However, different from the ordinary diagnosis function, a DTC will not be stored. The SRS warning light cannot be turned off. It is necessary to replace the airbag sensor assembly with a new one.