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Home >> Lexus >> 2021 >> LC 500 2D Coupe >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Airbag System - Diagnostic Codes (Coupe) (1 Of 5) >> Airbag System >> DTC B1617/84: Lost Communication with Front Airbag Sensor LH; DTC B1618/84: Front Airbag Sensor LH Initialization Incomplete [03/2017 - 04/2020] >> Procedure

DTC B1617/84: Lost Communication with Front Airbag Sensor LH; DTC B1618/84: Front Airbag Sensor LH Initialization Incomplete [03/2017 - 04/2020]: Procedure

  1. CHECK CONNECTION OF CONNECTORS 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Check that the connectors are properly connected to the airbag ECU assembly and front airbag sensor LH.

      Result

      Proceed to
      The connectors are properly connected
      The connectors are not properly connected

    Result: 

    The connectors are not properly connected 

    CONNECT CONNECTORS PROPERLY 

    Result: 

    The connectors are properly connected 

    See step  2

  2. CHECK CONNECTORS 
    1. Disconnect the connectors from the airbag ECU assembly and front airbag sensor LH.
    2. Check that the connectors (on the airbag ECU assembly side and front airbag sensor LH side) are not damaged.
      GTY506976Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Airbag Sensor LH
      *2 Airbag ECU Assembly
      *3 Engine Room Main Wire
      *4 Instrument Panel Wire

      Result

      Proceed to
      The connectors are not deformed or damaged
      The connectors are deformed or damaged

    Result: 

    The connectors are deformed or damaged 

    REPLACE INSTRUMENT PANEL WIRE OR ENGINE ROOM MAIN WIRE 

    Result: 

    The connectors are not deformed or damaged 

    See step  3

  3. CHECK FRONT AIRBAG SENSOR LH CIRCUIT 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
      GTY814603Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Airbag Sensor LH
      *2 Airbag ECU Assembly
      *3 Engine Room Main Wire
      *4 Instrument Panel Wire
      *5 Service Wire
      *a Front view of wire harness connector
      (to Front Airbag Sensor LH)
      *b Front view of wire harness connector
      (to Airbag ECU Assembly)
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A13-2 (+SL) - Body ground Engine switch on (IG) Below 1 V
      A13-1 (-SL) - Body ground Engine switch on (IG) Below 1 V
    4. Turn the engine switch off.
    5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    6. Using a service wire, connect terminals 30 (+SL) and 31 (-SL) of connector B.
      NOTE:

      Do not forcibly insert the service wire into the terminals of the connector when connecting a service wire.

    7. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A13-2 (+SL) - A13-1 (-SL) Always Below 1 Ω
    8. Disconnect the service wire from connector B.
    9. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A13-2 (+SL) - A13-1 (-SL) Always 1 MΩ or higher
      A13-2 (+SL) - Body ground Always 1 MΩ or higher
      A13-1 (-SL) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  5

    Result: 

    OK 

    See step  4

  4. CHECK FRONT AIRBAG SENSOR LH 
    1. Connect the connectors to the airbag ECU assembly.
      GTY799202Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Airbag Sensor RH
      *2 Airbag ECU Assembly
    2. Interchange the front airbag sensor LH with RH and connect the connectors to them.
    3. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    4. Turn the engine switch on (IG), and wait for at least 60 seconds.
    5. Clear the DTCs stored in memory.

      Refer to DTC CHECK / CLEAR [03/2017 - 04/2020]

      Body Electrical > SRS Airbag > Clear DTCs 

    6. Turn the engine switch off.
    7. Turn the engine switch on (IG), and wait for at least 60 seconds.
    8. Check for DTCs.

      Refer to DTC CHECK / CLEAR [03/2017 - 04/2020]

      Body Electrical > SRS Airbag > Trouble Codes 

      Result

      Proceed to
      DTC B1617/84 or B1618/84 is output
      DTC B1612/83 or B1613/83 is output
      DTC B1612/83, B1613/83, B1617/84 and B1618/84 are not output

      HINT: 

      Codes other than DTC B1612/83, B1613/83, B1617/84 and B1618/84 may be output at this time, but they are not related to this check.

    9. Turn the engine switch off.
    10. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    11. Return the front airbag sensor RH and LH to their original positions and connect the connectors to them.

    Result: 

    DTC B1617/84 or B1618/84 is output 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    DTC B1612/83 or B1613/83 is output 

    REPLACE FRONT AIRBAG SENSOR LH. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    DTC B1612/83, B1613/83, B1617/84 and B1618/84 are not output 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [03/2017 - 04/2020] 

  5. CHECK INSTRUMENT PANEL WIRE 
    1. Disconnect the instrument panel wire connector from the engine room main wire.
      GTY820917Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Airbag Sensor LH
      *2 Airbag ECU Assembly
      *3 Engine Room Main Wire
      *4 Instrument Panel Wire
      *5 Service Wire
      *a Front view of wire harness connector
      (to Engine Room Main Wire)
      *b Front view of wire harness connector
      (to Airbag ECU Assembly)
    2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    3. Turn the engine switch on (IG).
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      PA2-10 (+SL) - Body ground Engine switch on (IG) Below 1 V
      PA2-9 (-SL) - Body ground Engine switch on (IG) Below 1 V
    5. Turn the engine switch off.
    6. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    7. Using a service wire, connect terminals 30 (+SL) and 31 (-SL) of connector B.
      NOTE:

      Do not forcibly insert the service wire into the terminals of the connector when connecting a service wire.

    8. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      PA2-10 (+SL) - PA2-9 (-SL) Always Below 1 Ω
    9. Disconnect the service wire from connector B.
    10. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      PA2-10 (+SL) - PA2-9 (-SL) Always 1 MΩ or higher
      PA2-10 (+SL) - Body ground Always 1 MΩ or higher
      PA2-9 (-SL) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ENGINE ROOM MAIN WIRE 

    Result: 

    NG 

    REPLACE INSTRUMENT PANEL WIRE 

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