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Home >> Lexus >> 2005 >> GX 470 >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Supplemental Restraint System - Diagnostics >> Diagnosis System

Diagnosis System

  1. CHECK DLC3 
    1. The vehicle's ECM conforms to ISO 9141-2 for communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and meets the ISO 9141-2 format.
      Fig 1: Identifying DLC3 Connector terminals
      G02966517Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      DLC3 CONNECTOR TERMINALS VOLTAGE AND RESISTANCE

      Terminal no. Connection/Voltage or resistance Condition
      7 Bus + Line/Pulse generation During Transmission
      4 Chassis Ground <=> Body Ground/Below 1 Ω Always
      16 Battery Positives <=> Body Ground/10 to 14 V Always

      HINT:

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

      • If communication is normal when the tool is connected to another vehicle, inspect the DLC3 on the original vehicle.
      • If communication is still not possible when the tool is connected to another vehicle, the problem is probably in the tool itself. Consult the Service Department listed in the tool's instruction manual.
  2. 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 airbag system diagnosis (including the seat belt pretensioner and occupant classification system) is performed.

        HINT:

        If trouble is detected during the primary check, the SRS warning light remains on or blinks even after the primary check period (for approximately 6 seconds) has elapsed.

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

        HINT:

        If trouble is detected during the constant check, the airbag sensor assy center functions as follows:

        • The SRS warning light comes on or blinks.
        • The SRS warning light goes off, and then comes on. This blinking pattern indicates the source voltage drop. The SRS warning light goes 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 (for approximately 6 seconds after the ignition switch is turned to the ON position).

      2. When the airbag system has trouble:
        • The SRS warning light remains on or blinks even after the primary check period has elapsed.
        • The SRS warning light goes off after the primary check, but comes on or blinks again during the constant check.
        • The SRS warning light does not come on when turning the ignition switch from the LOCK to ON position.

          HINT:

          The airbag sensor assy center keeps the SRS waning light on if the airbag has been deployed.

  3. FUNCTION OF PASSENGER AIRBAG ON/OFF INDICATOR 
    1. Initial check.
      1. Turn the ignition switch to the ON position.
      2. The passenger airbag ON/OFF indicator ("ON" and "OFF") comes on for approximately 4 seconds, then goes off for approximately 2 seconds.
      3. Approximately 6 seconds after the ignition switch is turned to the ON position, the passenger airbag ON/OFF indicator will be ON/OFF depending on the conditions listed below.

        HINT:

        • If the front passenger seat condition and the indication by the passenger airbag ON/OFF indicator differ from those shown in FRONT PASSENGER SEAT CONDITION AND PASSENGER AIRBAG ON/OFF INDICATORS INDICATION  , and the SRS warning light is off, then the DTC is not output. If this occurs, perform troubleshooting of "Trouble in indicator of Passenger airbag ON/OFF indicator" (see TROUBLE IN INDICATOR OF PASSENGER AIRBAG ON/OFF INDICATOR ).
          FRONT PASSENGER SEAT CONDITION AND PASSENGER AIRBAG ON/OFF INDICATORS INDICATION

          Condition "ON" indicator "OFF" indicator
          Vacant OFF OFF
          Adult is seated. ON OFF
          Child is seated. OFF ON
          Child restraint system is set. OFF ON
          Front passenger occupant classification system failure. OFF ON
        • The passenger airbag ON/OFF indicator is based on the timing chart shown in Fig 2 in order to check the indicator light circuit
          Fig 2: Identifying Blinking Pattern Of Passenger Airbag ON/OFF Indicator
          G02966518Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
        • When the occupant classification system has trouble, both the SRS warning light and the passenger airbag ON/OFF indicator "OFF" come on. In this case, check the DTCs in the supplemental restraint system first. Then troubleshoot the occupant classification system if DTC B1150/23 is indicated and troubleshoot the passenger airbag ON/OFF indicator (supplemental restraint system) if DTC B1152/28 is detected.
  4. SRS WARNING LIGHT CHECK 
    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 goes off approximately 6 seconds after the ignition switch is turned to the ON position (constant check).
      Fig 3: Identifying SRS Warning Light
      G02966519Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      HINT:

      When any of the following symptoms occur, refer to the "Problem Symptoms Table" (see PROBLEM SYMPTOMS TABLE ).

      • The SRS warning light comes on occasionally, even after the primary check period has elapsed.
      • The SRS warning light comes on, but a DTC is not output.
      • The ignition switch is turned from the LOCK to ON position, but the SRS warning light does not come on.
  5. PASSENGER AIRBAG ON/OFF INDICATOR CHECK 
    1. Turn the ignition switch to the ON position.
    2. Check that the passenger airbag ON/OFF indicator ("ON" and "OFF") comes on for approximately 4 seconds, then goes off for approximately 2 seconds.

      HINT:

      Refer to the table shown in FRONT PASSENGER SEAT CONDITION AND PASSENGER AIRBAG ON/OFF INDICATORS INDICATION  regarding the passenger airbag ON/ OFF indicator when the ignition switch is turned to the ON position and approximately 6 seconds pass.

      Fig 4: Identifying Passenger Airbag ON/OFF Indicator
      G02966520Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  6. 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 (Refer to the illustrations shown in Fig 5, Fig 6 & Fig 7 .
      CAUTION: Never release the activation prevention mechanism on the squib connector even when inspecting with the squib disconnected.
      NOTE:
      • Never release the activation prevention mechanism unless specially directed 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.
      Fig 5: Activation Prevention Mechanism Release Method Chart (1 Of 2)
      G02966521Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      Fig 6: Activation Prevention Mechanism Release Method Chart (2 Of 2)
      G02966522Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      Fig 7: Identifying Airbag Sensor Assembly Connectors
      G02966523Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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