AIRBAG SYSTEM DIAGNOSIS SYSTEM


  1. CHECK DLC3

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    1. The vehicle ECM conforms to ISO 14230 and ISO 9141-2 communication protocol. The terminal arrangement of the DLC3 (Data Link Connector 3) complies with SAE J1962 and matches the ISO 14230 and ISO 9141-2 format.

      Symbols (Terminals No.) Terminal Description Condition Specified Condition
      SIL (7) - SG (5) Bus "+" line During transmission Pulse generation
      CG (4) - Body ground Chassis ground Always Below 1 Ω
      SG (5) - Body ground Signal ground Always Below 1 Ω
      BAT (16) - Body ground Battery positive Always 11 to 14 V

      Tech Tips

      If the display shows UNABLE TO CONNECT TO VEHICLE when you connect the cable of the intelligent tester to the DLC3, turn the ignition switch to the ON position and operate the intelligent tester, there is a problem on the vehicle side or the tester side.


      • If communication is normal when the tester is connected to another vehicle, inspect the DLC3 on the original vehicle.

      • If communication is still not possible when the tester is connected to another vehicle, the problem is probably in the tester itself. Consult the Service Department listed in the tester's instruction manual.

  2. SYMPTOM SIMULATION

    Tech Tips

    The most difficult case in troubleshooting is when no symptoms occur. In such cases, a thorough customer problem analysis must be carried out. Then conditions and an environment the same or similar to those in which the problem occurred in the customer's vehicle should be simulated. No matter how experienced or skilled a technician may be, if troubleshooting proceeds without confirmation of the problem symptoms, something important is likely to be overlooked and a wrong assumption may be made at some point in the repair operation. This leads to a standstill in troubleshooting.


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      Simulation method: When vibration seems to be the major cause

      Tech Tips

      Perform this method only during the primary check period (for approximately 6 seconds after the ignition switch is turned to the ON position).


      1. Use your finger to slightly vibrate the part of the sensor considered to be the problem cause, and check whether the malfunction recurs.

        Tech Tips

        Wiggling the relays too strongly may result in open relays.

      2. Gently wiggle the connector.

      3. Gently wiggle the wire harness. The connector joint and the pivot of the vibration are the areas that should be checked most thoroughly.

  3. FUNCTION OF SRS WARNING LIGHT


    1. Primary check


      1. Turn the ignition switch to the LOCK position. Wait for at least 2 seconds, then turn the ignition switch to the ON position. The SRS warning light comes on for approximately 6 seconds and the SRS airbag system diagnosis (including the seat belt pretensioner) is performed.

        Tech Tips

        If any malfunctions are detected during the primary check, the SRS warning light blinks even after the primary check period has elapsed.

    2. Constant check


      1. After the primary check, the center airbag sensor assembly constantly monitors the SRS airbag system for trouble.

        Tech Tips

        If any malfunctions are detected during the constant check, the center airbag sensor assembly functions as follows:


        • Blinks the SRS warning light.

        • Turns the SRS warning light off, and then blinks it again. This blinking pattern indicates the source voltage drop. The SRS warning light turns off 10 seconds after the source voltage returns to normal.

    3. Review


      1. When the airbag system is normal:

        The SRS warning light comes on only during the primary check period (approximately 6 seconds after the ignition switch is turned to the ON position).

        Tech Tips

        The SRS warning light remains illuminated while the airbag cut-off switch is off.

      2. When the airbag system malfunctions:


        • The SRS warning light blinks after the primary check period has elapsed.

        • The SRS warning light turns off after the primary check, but blinks during the constant check.

        • The SRS warning light remains off even after the ignition switch is turned from LOCK to ON. However, if malfunctions such as an open circuit have occurred in the wire harness between the meter and ECU, the warning light blinks 10 seconds after the ignition switch is turned on.

          Tech Tips

          The center airbag sensor assembly keeps the SRS warning light blinking on if the airbag has been detected any malfunction.

  4. SRS WARNING LIGHT CHECK

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    1. Turn the ignition switch to the ON position, and check that the SRS warning light comes on for approximately 6 seconds (primary check).

    2. Check that the SRS warning light turns off approximately 6 seconds after the ignition switch is turned to the ON position (constant check).

      Tech Tips

      When any of the following symptoms occur, refer to the Problem Symptoms Table Click here.


      • The SRS warning light blinks occasionally, after the primary check period has elapsed.

      • Even when the SRS warning light blinks, no DTC is set.

      • Even when the ignition switch is turned from the LOCK to ON position, the SRS warning light remains off.

  5. RELEASE METHOD OF ACTIVATION PREVENTION MECHANISM


    1. The activation prevention mechanism is built into the connector for the squib circuit of the SRS. As explained in the troubleshooting section, insert a piece of paper that is the same thickness as the male terminal between the terminal and the short spring to release it.

      CAUTION:

      Never release the activation prevention mechanism on the squib connector even when inspecting with the squib disconnected.

      Note


      • Do not release the activation prevention mechanism unless specially directed to do so by the troubleshooting procedure.

      • To prevent the terminal and the short spring from being damaged, always use a piece of paper that is the same thickness as the male terminal.

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