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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Airbag System - Diagnostic Codes (5 Of 7) >> Airbag System >> DTC B1617: Front Airbag Sensor Lost Communication (LH); DTC B1618: Front Airbag Sensor Initialization Error (LH) [12/2019 - 11/2023] >> Procedure

DTC B1617: Front Airbag Sensor Lost Communication (LH); DTC B1618: Front Airbag Sensor Initialization Error (LH) [12/2019 - 11/2023]: Procedure

  1. CHECK CONNECTION OF CONNECTORS 
    1. Turn the ignition switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    3. Check that the connectors are properly connected to the airbag sensor assembly and front airbag sensor LH. Also check that the connectors that link the engine room main wire and instrument panel wire are properly connected.

      OK

      The connectors are properly connected.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    CONNECT CONNECTORS PROPERLY 

    Result: 

    OK 

    See step  2

  2. CHECK CONNECTORS 
    1. Disconnect the connectors from the airbag sensor assembly and front airbag sensor LH. Also disconnect the connectors that link the engine room main wire and instrument panel wire.
    2. Check that the terminals of the connectors are not deformed or damaged.

      OK

      The terminals are not deformed or damaged.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE INSTRUMENT PANEL WIRE OR ENGINE ROOM MAIN WIRE 

    Result: 

    OK 

    See step  3

  3. CHECK FRONT AIRBAG SENSOR LH CIRCUIT 
    1. Connect the connectors that link the engine room main wire and instrument panel wire.
      GTY906963Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Airbag Sensor LH
      *2 Airbag Sensor Assembly
      *3 Engine Room Main Wire
      *4 Instrument Panel Wire
      *5 Service Wire
      *a Front view of wire harness connector
      (to Airbag Sensor Assembly)
      *b Front view of wire harness connector
      (to Front Airbag Sensor LH)
    2. Connect the cable to the negative (-) auxiliary battery terminal.
    3. Turn the ignition switch to ON.
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A49-2 (+SL) - Body ground Ignition switch ON Below 1 V
      A49-1 (-SL) - Body ground Ignition switch ON Below 1 V
    5. Turn the ignition switch off.
    6. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    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 the wire.

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      A49-2 (+SL) - A49-1 (-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
      A49-2 (+SL) - A49-1 (-SL) Always 1 MΩ or higher
      A49-2 (+SL) - Body ground Always 1 MΩ or higher
      A49-1 (-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 connector to the airbag sensor assembly.
      GTY449974Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Airbag Sensor RH
      *2 Airbag Sensor Assembly
    2. Interchange the front airbag sensor LH with RH and connect the connectors.
    3. Connect the cable to the negative (-) auxiliary battery terminal.
    4. Turn the ignition switch to ON, and wait for at least 60 seconds.
    5. Clear the DTCs stored in memory.

      Body Electrical > SRS Airbag > Clear DTCs 

    6. Turn the ignition switch off.
    7. Turn the ignition switch to ON, and wait for at least 60 seconds.
    8. Check for DTCs.

      Body Electrical > SRS Airbag > Trouble Codes 

      HINT: 

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

      Result

      Result Proceed to
      DTCs B1612, B1613, B1617 and B1618 are not output. A
      DTC B1617 or B1618 is output. B
      DTC B1612 or B1613 is output. C
    9. Turn the ignition switch off.
    10. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    11. Return the front airbag sensor LH and RH to their original positions and connect the connectors.

    Result: 

    A 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ] 

    Result: 

    B 

    REPLACE AIRBAG SENSOR ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

    Result: 

    C 

    REPLACE FRONT AIRBAG SENSOR LH. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

  5. CHECK INSTRUMENT PANEL WIRE 
    1. Disconnect the instrument panel wire connector from the engine room main wire.
      GTY912949Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Airbag Sensor LH
      *2 Airbag Sensor Assembly
      *3 Engine Room Main Wire
      *4 Instrument Panel Wire
      *5 Service Wire
      *a Front view of wire harness connector
      (to Airbag Sensor Assembly)
      *b Front view of wire harness connector
      (to Engine Room Main Wire)
    2. Connect the cable to the negative (-) auxiliary battery terminal.
    3. Turn the ignition switch to ON.
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      AH5-2 (+SL) - Body ground Ignition switch ON Below 1 V
      AH5-4 (-SL) - Body ground Ignition switch ON Below 1 V
    5. Turn the ignition switch off.
    6. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    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 the wire.

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      AH5-2 (+SL) - AH5-4 (-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
      AH5-2 (+SL) - AH5-4 (-SL) Always 1 MΩ or higher
      AH5-2 (+SL) - Body ground Always 1 MΩ or higher
      AH5-4 (-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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