AIRBAG SYSTEM


  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, front passenger knee airbag, curtain shield airbags and seat belt pretensioners should be deployed. It also diagnoses system malfunctions.

      • The airbag sensor assembly receives signals from either side airbag sensor or No. 2 side airbag sensor 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 side airbag, curtain shield airbag and seat belt pretensioners should be deployed. It also diagnoses system malfunctions.
      Horn Button Assembly Driver Airbag The airbags are used as supplements to the seat belts to help reduce impact to the occupants.
      Instrument Panel Passenger Airbag Assembly Front Passenger Airbag
      Instrument Panel Airbag Assembly Lower No. 1/No. 2 Driver Knee Airbag/Front Passenger Knee Airbag
      Front Seat Airbag Assembly LH/RH Front Side Airbag LH/RH
      Curtain Shield Airbag Assembly LH/RH Curtain Shield Airbag 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 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.
      No. 2 Side Airbag Sensor LH/RH
      Seat Position Airbag Sensor The seat position sensor detects the slide position of the driver seat.
      Front Seat Outer Belt Assembly Driver and Front Passenger The front seat outer belt assemblies are used as supplements to help reduce impact to the occupants.
      Rear Seat Outer Belt Assembly* Rear Passenger LH/RH The rear seat outer belt assemblies are used as supplements to help reduce impact to the occupants.
      Front Seat Inner Belt Assembly Driver Seat Belt Buckle Switch The driver seat belt buckle switch detects if the driver seat belt is fastened.
      Front Passenger Seat Belt Buckle Switch The front passenger seat belt buckle switch detects if the front passenger 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 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.
      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.

      *: Models with rear seat outer belt pretensioner

  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 and pretensioner 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 front seat belt pretensioners, rear seat outer belt pretensioners and airbags except the front side airbags.

        A004V43E03

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

        *: Models with rear seat outer belt pretensioner

        A004V2EE03

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

        *: Models with rear seat outer belt pretensioner

        A004UZXE03

  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 assembly, instrument panel airbag assembly lower No. 1, instrument panel airbag assembly lower No. 2 and curtain shield airbag assemblies. These airbags deploy simultaneously. The horn button assembly and instrument panel passenger airbag assembly use dual-stage control.

      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 assembly, instrument panel airbag assembly lower No. 1, instrument panel airbag assembly lower No. 2 and curtain shield airbag assemblies to deploy. At the same time, the airbag sensor assembly deploys the front the seat belt pretensioners and rear seat outer belt pretensioners*.

        *: Models with rear seat outer belt pretensioner

        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 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
        Seat Belt Condition Front Seat Inner Belt Assembly (Front Passenger Seat Belt Buckle Switch) (Non-contact Type)
        A004V5PE03

    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 belt pretensioner and rear seat outer belt pretensioner* are also deployed.

      2. For a side collision, if the side airbag sensor or No. 2 side airbag sensor detects an impact, it informs the airbag sensor assembly, and the airbag sensor assembly causes the front seat airbag assembly, curtain shield airbag assembly, front seat belt pretensioner and rear seat outer belt pretensioner* on the collision side to deploy.

        *: Models with rear seat outer belt pretensioner

        A004UWAE03

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

        *: Models with rear seat outer belt pretensioner

        A004V7SE04

    3. Airbag Cut Off Switch Cylinder Sub-assembly (Models with Airbag Cut Off Switch)


      1. The airbag cut off switch cylinder sub-assembly can be used if the deployment of the instrument panel passenger airbag assembly and instrument panel airbag assembly lower No. 2 is undesirable.

      2. The airbag cut off switch cylinder sub-assembly can be operated by the mechanical key which is supplied with the key. Once the airbag cut off switch cylinder sub-assembly is turned to OFF, the instrument panel passenger airbag assembly and instrument panel airbag assembly lower No. 2 will be disabled, regardless of any collision that may occurs.

      3. If the instrument panel passenger airbag assembly and instrument panel airbag assembly lower No. 2 have been disabled, the AIRBAG OFF indicator light in the combination switch assembly will illuminate to inform the driver.

        B0022DI

      4. The table below shows the operation of the front passenger airbag and the AIRBAG OFF indicator light condition according to the airbag cut off switch cylinder sub-assembly status.

        Item Airbag Cut Off Switch Cylinder Sub-assembly Status
        ON OFF Failure
        Passenger Instrument Panel Passenger Airbag Assembly Enabled Disabled Disabled
        Seat Belt Pretensioner Enabled Enabled Enabled
        Instrument Panel Airbag Assembly Lower No. 2 Enabled Disabled Disabled
        AIRBAG OFF Indicator Light Not Illuminated Illuminated Illuminated

    4. 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, airbag deployment 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 power switch is turned on (IG), the airbag sensor assembly operates the AIRBAG ON/OFF indicator lights as shown below to check for an open in the indicator light circuits.

        B0022M2E58

  4. CONSTRUCTION


    1. Airbag Sensor Assembly


      1. The airbag sensor assembly consists of judgment circuits, a safing sensor, ignition control circuit, 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 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 sensors and No. 2 side 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 code 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.

        A004V42E03
        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 Assembly


      1. Instrument panel passenger airbag 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 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 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.

        A004V3WE02
        Text in Illustration
        *1 1st Initiator Connector *2 2nd Initiator Connector
        *3 Inflator *4 Bag
        *5 Depression - -
        *a A-A Cross Section - -

    4. Instrument Panel Airbag Assembly Lower No. 1 and Instrument Panel Airbag Assembly Lower No. 2


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

        A004V7EE03
        Text in Illustration
        *1 Instrument Panel Airbag Assembly Lower No. 1 *2 Instrument Panel Airbag Assembly Lower No. 2
        *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 bag.

        A004UZSE03
        Text in Illustration
        *1 Front Seat Airbag Assembly *2 Inflator
        *3 Bag - -
        *a A-A Cross Section *b B-B Cross Section

    6. Curtain Shield Airbag Assembly


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

        A004V4YE03
        Text in Illustration
        *1 Curtain Shield Airbag Assembly *2 Inflator
        *3 Bag - -
        *a A-A Cross Section - -

    7. 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 an internal element of the sensor and is converted into an electrical signal.

        A004UXQE30
        *1 Front Airbag Sensor
        *2 Deceleration Sensor
        *3 Airbag Sensor Assembly
        *4 Communication IC

    8. Side Airbag Sensor and No. 2 Side Airbag Sensor


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

        A004V92E30

    9. Seat Position Airbag Sensor


      1. The seat position airbag sensor, which uses a Hall IC, detects changes in the magnetic flux that occurs due to the movement of the upper rail.

        A004UUTE03
        Text in Illustration
        *A Models with Power Seat *B Models without Power Seat
        *1 Seat Position Airbag Sensor - -
        *a Seat position is rearward *b Seat position is forward

    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.

        A004UPJE21
        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 intelligent tester.

    3. The 5-digit DTCs can be read by connecting the intelligent tester to the DLC3. For details, refer to the Repair Manual.

    4. If an SRS airbag deploys, 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.