AIRBAG SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components of the SRS System have the following functions:

      Component Function
      Airbag ECU Assembly

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

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

      • The airbag ECU assembly sends an airbag deployment signal to the ECM through the Controller Area Network (CAN) to operate fuel pump control.
      Horn Button Assembly Driver Side Squib 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/No. 2 Instrument Panel Airbag Assembly Driver Knee Airbag Squib/Front Passenger Knee Airbag Squib
      Front Seat Airbag Assembly LH/RH Front 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, distortion is created in the sensor and is converted into an electrical signal.
      Side Airbag Sensor Assembly LH/RH Based on the deceleration of the vehicle during a side or rear side collision, distortion is created in the sensor and is converted into an electrical signal.
      Side Door Airbag Sensor LH/RH
      Rear Airbag Sensor LH/RH
      Front Seat Outer Belt Assembly LH/RH Front Pretensioner Squib LH/RH Used to help reduce impact to the occupants.
      Rear Seat 3 Point Type Outer Belt Assembly LH/RH Rear Pretensioner Squib LH/RH
      Seat Position Airbag Sensor Detects the slide position of the driver seat.
      Driver Seat Belt Buckle Switch (Front Seat Inner Belt Assembly LH*1/RH*2) Detects if the driver seat belt is fastened.
      Airbag Cut Off Switch Cylinder Sub-assembly*3 Suspends the instrument panel passenger airbag without door assembly operation.
      Air Conditioning Control Assembly

      • AIRBAG OFF Indicator Light*3

      • AIRBAG ON Indicator Light*3

      		 Inform the occupants of the airbag cut off switch cylinder sub-assembly status.
      Combination Meter Assembly SRS Warning Light Turns on to alert the driver when the airbag ECU assembly detects a malfunction in the airbag system.
      Multi-information Display Displays a warning message to inform the driver of a malfunction in the system.
      Master Warning Light Turns on to alert the driver when the airbag ECU assembly detects a malfunction in the system.
      Buzzer Sounds to warn the driver of a malfunction in the system.

      *1: LHD models

      *2: RHD models

      *3: Models with airbag cut off switch cylinder

  2. SYSTEM CONTROL


    1. Airbag for Frontal Collision


      1. There are 8 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, lower No. 2 instrument panel airbag assembly, front seat airbag assemblies and curtain shield airbag assemblies. These airbags deploy simultaneously. The horn button assembly and instrument panel passenger airbag without door assembly use dual-stage control. In addition, the front pretensioners contained in the front seat outer belt assemblies LH and RH, and rear pretensioners contained in the rear seat 3 point type outer belt assembly LH and RH are also activated.

      2. The airbag ECU assembly detects the information in the table below from various sources in order to activate the dual-stage control.

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

        Airbag Information Source
        Driver Extent of Impact

        • Front Airbag Sensor LH or RH

        • Airbag ECU Assembly
        Driver Seat Position Seat Position Airbag Sensor
        Seat Belt Condition Driver Seat Belt Buckle Switch (Front Seat Inner Belt Assembly LH*1/RH*2) (Non-contact Type)
        Front Passenger Extent of Impact

        • Front Airbag Sensor LH or RH

        • Airbag ECU Assembly

        *1: LHD models

        *2: RHD models

        A01VMI1E01

      4. 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.

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

      6. Frontal collision signals are produced based on the information from the airbag ECU 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


      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. Additionally, at the same time, the front seat outer belt assembly is also activated.

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

        A01VMCLE01

      3. The front seat airbag assembly and curtain shield airbag assembly are deployed and the front pretensioner in the front seat outer belt assembly LH or RH is activated based on signals from the side door airbag sensors or side airbag sensor assemblies and airbag ECU assembly.

        Figure 2. Side Collision

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      4. For a rear side collision, if the rear airbag sensor detects an impact, it informs the airbag ECU assembly and the airbag ECU assembly causes the curtain shield airbag assembly to deploy.

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

        Figure 3. Rear Side Collision

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    3. Primary Check Illumination Control


      1. After the engine switch is turned on (IG), the airbag ECU 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 ECU assembly is performed. If a malfunction is detected during the primary check, the SRS warning light will remain on even after 6 seconds have elapsed.

      2. After the engine switch is turned on (IG), the airbag ECU assembly operates the passenger airbag ON/OFF indicator lights as shown below to check for an open in the indicator light circuits.

        A01VMBTE25

  3. DIAGNOSIS


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

    2. The airbag ECU assembly outputs malfunction data and 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.

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