AIRBAG SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components of the SRS 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, driver knee airbag, front seat airbags, front seat airbag sub-assembly RH*1 and curtain shield airbags should be deployed and the front seat belt pretensioners are activated. 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 or rear airbag sensor. 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 side sensors and the safing sensor, the airbag sensor assembly determines whether the front seat airbag assemblies and curtain shield airbag assemblies should be deployed. The airbag sensor assembly 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 the airbag deployment signal to the main body ECU (multiplex network body ECU) to operate the collision door lock release function.*2
      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 Instrument Panel Airbag Assembly Driver Knee Airbag Squib
      Front Seat Airbag Assembly LH/RH Front Side Airbag Squib LH/RH
      Front Seat Airbag Sub-assembly RH*1 Front Seat Cushion Airbag Squib 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.
      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.
      Seat Position Airbag Sensor Detects the slide position of the driver seat.
      Driver Seat Belt Buckle Switch (Front Seat Inner Belt Assembly LH*3/RH*4) Detects if the driver seat belt is fastened.
      Front Passenger Seat Belt Buckle Switch (Front Seat Inner Belt Assembly RH*3) Detects if the front passenger seat belt is fastened.
      ECM The fuel pump is stopped when an SRS airbag is deployed in a frontal collision, side collision or rear side collision.
      Main Body ECU (Multiplex Network Body ECU)*2 Receives an airbag deployment signal from the airbag sensor assembly and operates the collision door lock release function.
      DCM (Telematics Transceiver)*5 Receives an airbag deployment signal from the airbag sensor assembly, and automatically makes the emergency call of automatic collision notification service.
      Airbag Cut Off Switch Cylinder Sub-assembly*6 Suspends the instrument panel passenger airbag without door assembly and front seat airbag sub-assembly RH*1 operation.
      Clock Assembly*6 AIRBAG ON/OFF Indicator Light 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 sensor assembly detects a malfunction in the airbag system.

      *1: Models with seat cushion airbag

      *2: Models with collision door lock release function

      *3: LHD models

      *4: RHD models

      *5: Models with manual (SOS) switch

      *6: Models with airbag cut off 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, front seat airbag assemblies, front seat airbag sub-assembly RH* 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, each front pretensioner contained in a front seat outer belt assembly is also activated.

        *: Models with seat cushion airbag

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

        Airbag Information Source
        Driver Extent of Impact

        • Front Airbag Sensor LH or RH

        • Airbag Sensor 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 Sensor Assembly
        Seat Belt Condition Front Passenger Seat Belt Buckle Switch (Front Seat Inner Belt Assembly RH) (Non-contact Type)*1

        *1: LHD models

        *2: RHD models

      3. 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, lower No. 1 instrument panel airbag assembly, front seat airbag assemblies, front seat airbag sub-assembly RH* and curtain shield airbag assemblies to deploy. Additionally, the airbag sensor assembly activates the seat belt pretensioners for the driver and front passenger.

        *: Models with seat cushion airbag

        A0025TEE01
        A0025Y3E01

      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 sensor 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 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

        A0025MPE01

    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.

      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 and curtain shield airbag assembly to deploy simultaneously.

        A0025VSE01

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

        Figure 2. Side Collision

        A0025WWE01

      4. For a rear side collision, if the rear airbag sensor 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 to deploy.

        A0025PBE01

      5. The curtain shield airbag assembly is deployed based on signals from the rear airbag sensor and the airbag sensor assembly.

        Figure 3. Rear Side Collision

        A00263TE01

    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 a malfunction is detected during the primary check, the SRS warning light will remain on even after 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.

        A0025MVE48

  3. 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 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 sensor 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 sensor assembly with a new one.