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Home >> Toyota >> 2022 >> Avalon XLE >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 64 (Occupant Classification System - Diagnostic Codes & Symptom Tests (Hybrid)) >> OCCUPANT CLASSIFICATION SYSTEM (for HV Model) >> DTC B1771: Passenger Side Buckle Switch Circuit Malfunction [04/2018 - ] >> Procedure

DTC B1771: Passenger Side Buckle Switch Circuit Malfunction [04/2018 - ]: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. CHECK CONNECTORS 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
    3. Check that the connectors are properly connected to the occupant detection ECU and front seat inner belt assembly RH.

      OK

      The connectors are properly connected.

      HINT: 

      If the connectors are not properly connected, reconnect the connectors and proceed to the next inspection.

    4. Disconnect the connectors from the occupant detection ECU and front seat inner belt assembly RH.
    5. 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 FRONT SEAT WIRE RH 

    Result: 

    OK 

    See step  2

  2. CHECK FRONT SEAT WIRE RH 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
      GTY942016Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Inner Belt Assembly RH
      *2 Occupant Detection ECU
      *3 Front Seat Wire RH
      *4 Service Wire
      *a Front view of wire harness connector
      (to Occupant Detection ECU)
      *b Front view of wire harness connector
      (to Front Seat Inner Belt Assembly RH)
    2. Turn the power switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      R7-7 (BSW) - Body ground Power switch on (IG) Below 1 V
      R7-9 (BGND) - Body ground Power switch on (IG) Below 1 V
    4. Turn the power switch off.
    5. Disconnect the cable from the negative (-) auxiliary battery terminal.
    6. Using a service wire, connect terminals 2 (BSW) and 1 (BGND) of connector C.
      NOTE:

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

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      R7-7 (BSW) - R7-9 (BGND) Always Below 1 Ω
    8. Disconnect the service wire from connector C.
    9. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      R7-7 (BSW) - R7-9 (BGND) Always 1 MΩ or higher
      R7-7 (BSW) - Body ground Always 1 MΩ or higher
      R7-9 (BGND) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FRONT SEAT WIRE RH 

    Result: 

    OK 

    See step  3

  3. CHECK DTC 
    1. Connect the connectors to the occupant detection ECU and front seat inner belt assembly RH.
    2. Connect the cable to the negative (-) auxiliary battery terminal.
    3. Turn the power switch on (IG), and wait for at least 60 seconds.
    4. Clear the DTCs stored in the occupant detection ECU.

      Body Electrical > Occupant Detection > Clear DTCs 

    5. Clear the DTCs stored in the airbag ECU assembly.

      Body Electrical > SRS Airbag > Clear DTCs 

    6. Turn the power switch off.
    7. Turn the power switch on (IG), and wait for at least 10 seconds.
    8. Check for DTCs.

      Body Electrical > Occupant Detection > Trouble Codes 

      OK

      DTC B1771 is not output.

      HINT: 

      Codes other than DTC B1771 may be output at this time, but they are not related to this check.

    9. Turn the power switch off.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [04/2018 - ] 

    Result: 

    NG 

    See step  4

  4. CHECK FRONT SEAT INNER BELT ASSEMBLY RH 
    1. Disconnect the cable from the negative (-) auxiliary battery terminal.
    2. Replace the front seat inner belt assembly RH with a known good one.

      Refer to REMOVAL [04/2018 - 08/2021] , or refer to REMOVAL [08/2021 - ]

      HINT: 

      Perform the following inspection using known good parts from another vehicle if possible.

    3. Connect the cable to the negative (-) auxiliary battery terminal.
    4. Turn the power switch on (IG), and wait for at least 60 seconds.
    5. Clear the DTCs stored in the occupant detection ECU.

      Body Electrical > Occupant Detection > Clear DTCs 

    6. Clear the DTCs stored in the airbag ECU assembly.

      Body Electrical > SRS Airbag > Clear DTCs 

    7. Turn the power switch off.
    8. Turn the power switch on (IG), and wait for at least 10 seconds.
    9. Check for DTCs.

      Body Electrical > Occupant Detection > Trouble Codes 

      OK

      DTC B1771 is not output.

      HINT: 

      Codes other than DTC B1771 may be output at this time, but they are not related to this check.

    10. Turn the power switch off.
    11. Disconnect the cable from the negative (-) auxiliary battery terminal.
    12. Restore the front seat inner belt assembly RH that was installed for testing to its original location.

      Refer to REMOVAL [04/2018 - 08/2021] , or refer to REMOVAL [08/2021 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FRONT SEAT INNER BELT ASSEMBLY RH. Refer to  REMOVAL [04/2018 - 08/2021]  , or refer to  REMOVAL [08/2021 - ] 

    Result: 

    NG 

    See step  5

  5. REPLACE OCCUPANT DETECTION ECU 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
    3. Replace the occupant detection ECU with a new one.

      Refer to REMOVAL [04/2018 - 08/2021] , or refer to REMOVAL [08/2021 - ]

    4. Connect the cable to the negative (-) auxiliary battery terminal.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  6

  6. PERFORM ZERO POINT CALIBRATION 
    1. Using the Techstream, perform Zero Point Calibration.

      Refer to INITIALIZATION [04/2018 - ]

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    END 

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