AIRBAG SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components of the supplemental restraint 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 side airbag, front passenger side airbag, driver knee airbag, front passenger knee airbag, curtain shield airbags, front seat belt pretensioners and rear 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 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, rear 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.

      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/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
      Rear Seat Airbag Assembly LH/RH 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, 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 The front seat outer belt assemblies are used to help reduce impact to the occupants.
      Rear Seat 3 Point Type Outer Belt Assembly LH/RH Rear Pretensioner Squib LH/RH The rear seat outer belt assemblies are used to help reduce impact to the occupants.
      Driver Seat Belt Buckle Switch (Front Seat Inner Belt Assembly LH*1/RH*2) The driver seat belt buckle switch detects if the driver seat belt is fastened.
      Power Management Control ECU
      • The power management control ECU receives an airbag deployment signal from the airbag sensor during a frontal collision, side or rear side collision.

      • The power management control ECU will shut down the hybrid system power supply by turning the System Main Relays (SMRs) off, in order to ensure safety.

      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: LHD models

      *2: RHD models

  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 and activate the pretensioners as indicated in the table below. The side airbags and rear side airbags are not deployed in a frontal collision.

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      4. The front seat airbag assembly, rear seat airbag assembly and curtain shield airbag assembly are deployed based on signals from the side airbag sensor assemblies and airbag sensor assembly.

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      5. The rear seat airbag assembly and curtain shield airbag assembly are deployed based on signals from the rear airbag sensors or the side airbag sensor assemblies and the airbag sensor assembly.

        A0003AME04
  3. SYSTEM CONTROL


    1. Airbag for Frontal Collision


      1. There are 6 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 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 pretensioners contained in the front and rear seat outer belt assemblies LH and RH are also activated.

      2. The airbag sensor 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 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, lower No. 2 instrument panel airbag assembly and curtain shield airbag assemblies to deploy. Additionally, the airbag sensor 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 Sensor Assembly

        Seat Belt Condition Front Seat Inner Belt Assembly (Driver Seat Belt Buckle Switch) (Non-contact Type)
        Front Passenger Extent of Impact
        • Front Airbag Sensor (LH or RH)

        • Airbag Sensor Assembly

        Rear Passenger Extent of Impact
        • Front Airbag Sensor (LH or RH)

        • Airbag Sensor Assembly

        A0002SZE02
    2. Airbag for Side/Rear Side 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.

      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.

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      3. 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 and rear seat airbag assembly to deploy.

        A0002MFE01
    3. Primary Check Illumination Control


      1. After the power switch is turned on (IG), 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.

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  4. CONSTRUCTION


    1. Airbag Sensor Assembly


      1. The airbag sensor assembly consists of a judgment circuit, deceleration sensor, ignition control circuit, safing sensor, backup power circuit, 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 rear 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 rear airbag sensors. If the calculated values are greater than the specified values, the airbags are deployed.
        Safing Sensor During a frontal, side or rear side 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 the system for 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 a set of 2 initiators and propellants. The airbag sensor assembly helps optimize the airbag deployment rate by controlling the ignition timing of the initiators.

        A0002MSE05
        Text in Illustration
        *1 Bag *2 Inflator
        *3 1st Initiator Connector *4 2nd 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 a set of 2 initiators and propellants. The airbag sensor assembly helps optimize the airbag deployment rate by controlling the ignition timing of these initiators.

      2. When the instrument panel passenger airbag without door assembly is deployed, it forms the shape of 2 bags with a depression in the middle. Immediately after the airbag is deployed, the shape of 2 bags supports 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 1st Initiator Connector *2 2nd Initiator Connector
        *3 Inflator *4 Bag
        *5 Depression - -
        *a A-A Cross Section - -
    4. Lower No. 1 Instrument Panel Airbag Assembly and Lower No. 2 Instrument Panel Airbag Assembly


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

        A0002ZRE01
        Text in Illustration
        *1 Lower No. 1 Instrument Panel Airbag Assembly *2 Lower No. 2 Instrument Panel Airbag Assembly
        *3 Inflator *4 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.

        A0002ZQE05
        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.

        A0002WUE05
        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.

        A00033YE04
        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, distortion is created in the internal element in the sensor and is converted into an electrical signal.

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        *1 Front Airbag Sensor
        *2 Deceleration Sensor
        *3 Airbag Sensor Assembly
        *4 Communication Circuit
    9. Side Airbag Sensor Assembly and Rear Airbag Sensor


      1. A deceleration sensor is built into each side airbag sensor assembly and rear airbag sensor. As a result of the deceleration of the vehicle during a side or rear side collision, distortion is created in the internal element in the sensor and is converted into an electrical signal.

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    10. Front Seat Inner Belt Assembly (Seat Belt Buckle Switch)


      1. A non-contact type switch is built into the front seat inner belt assembly (seat belt buckle switch) on the driver and front passenger sides.

      2. The non-contact type switch contains a Hall IC and magnet.

      3. The ejector inside a front seat inner belt assembly (seat belt buckle switch) and the plate installed to the ejector, move when the seat belt is removed or inserted. The movement of the plate changes the magnetic flux density of the magnet.

      4. The Hall IC detects changes in the magnetic flux density. These changes indicate that the seat belt is either fastened or unfastened, and the Hall IC outputs a signal to the airbag sensor assembly (for driver).

        A0002Z7E17
        Text in Illustration
        *1 Ejector *2 Magnet
        *3 Hall IC *4 Plate
        *5 Magnetic Flux - -
        *a Seat belt not fastened *b Seat belt fastened
  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 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 illuminate 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.