AIRBAG SYSTEM DETAILS


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components have the following functions:

      Component Function
      Airbag Sensor Assembly

      • In the event of a 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 sensors and the safing sensor, the airbag sensor assembly determines whether the horn button assembly (driver airbag), instrument panel passenger without door airbag assembly (front passenger airbag), lower No. 1 instrument panel airbag assembly (driver knee airbag), lower No. 2 instrument panel airbag assembly (front passenger knee airbag), curtain shield airbag assemblies, and front seat belt pretensioners should be deployed. The airbag sensor assembly also diagnoses system malfunctions.

      • In the event of a collision, the airbag sensor assembly receives signals from the door side airbag sensors, side airbag sensor assemblies or side No. 2 airbag sensor assemblies. 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, curtain shield airbag assemblies and front seat belt pretensioner should be deployed. The airbag sensor assembly also diagnoses system malfunctions.
      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, 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 rear side collision, a distortion is created in the sensor and converted into an electrical signal.
      Side No. 2 Airbag Sensor assembly LH/RH
      Door Side 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.
      Driver Seat Belt Buckle Switch (Front Seat Inner Belt Assembly LH) The driver seat belt buckle switch detects if the driver seat belt is fastened.
      Front Passenger Seat Belt Buckle Switch (Front Seat Inner Belt Assembly RH) The front passenger seat belt buckle switch detects if the front passenger seat belt is fastened.
      Occupant Detection ECU The occupant detection ECU judges whether the front passenger seat is occupied based on signals from the 2 occupant detection sensors and the front passenger seat belt buckle switch.
      Occupant Detection Sensor (Rear LH/RH) The sensors are strain gauge type sensors that send signals to the occupant detection ECU in accordance with the weight of the occupant.
      Power Management Control ECU

      • The power management control ECU receives an airbag deployment signal from the airbag sensor during a frontal collision or 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.
      ECM The fuel pump is stopped when an SRS airbag is deployed in a frontal, side, or rear side collision.
      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.

  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.

        A01HS66E02

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

        A01HRWKE02

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

        A01HRWPE02

  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 without door airbag assembly use dual-stage control.

      2. The airbag sensor assembly detects the information indicated 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. Meanwhile, the airbag sensor assembly activates the seat belt pretensioners for the driver and front passenger.

        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
        Occupant Detection

        2 Occupant Detection Sensors

        (Connected to the airbag sensor assembly through the occupant detection ECU.)
        Seat Belt Condition

        Front Seat Inner Belt Assembly (Front Passenger Seat Belt Buckle Switch) (Non-contact Type)

        (Connected to the airbag sensor assembly through the occupant detection ECU.)
        A01HS6PE01

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

      2. For a side collision, if the door side airbag sensor, side airbag sensor assembly detects an impact, via the side No. 2 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.

        A01HS4XE01

      3. For a rear side collision, if the side No. 2 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.

        A01HRVXE03

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

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

        A01HRZ1E07

  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, door side airbag sensors, side airbag sensors and side No. 2 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, door side airbag sensors, side airbag sensor assemblies and side No. 2 airbag sensor assemblies. 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 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 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.

        A01HRYWE01
        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 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.

        A01HS1UE01
        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.

        A01HS1ZE01
        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.

        A01HS7QE01
        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.

        A01HRZRE01
        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.

        A01HS0UE01
        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.

        A01HRZFE02

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


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

        A01HRTLE01

    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 the 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) or occupant detection ECU (for front passenger).

        A01HS53E08
        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 the malfunction data and 5-digit Diagnostic Trouble Codes (DTCs) to the Techstream.

    3. The 5-digit DTCs can be read after connecting the Techstream 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.