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Home >> Lexus >> 2017 >> GX 460 Base >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Occupant Classification System (Diagnostic Codes & Symptom Tests) >> Occupant Classification System >> DTC B1771: Passenger Side Buckle Switch Circuit Malfunction [08/2015 - 08/2019] >> Procedure

DTC B1771: Passenger Side Buckle Switch Circuit Malfunction [08/2015 - 08/2019]: Procedure

  1. CHECK FOR DTC 
    1. Turn the engine switch on (IG), and wait for at least 60 seconds.
    2. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      HINT: 

      First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.

    3. Turn the engine switch off.
    4. Turn the engine switch on (IG), and wait for at least 60 seconds.
    5. Check for DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      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.

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK 

    (Refer to DIAGNOSIS SYSTEM [08/2015 - ] )

    Result: 

    NG 

    See step  2

  2. CHECK CONNECTION OF CONNECTOR 
    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 occupant classification ECU and front seat inner belt RH.

      OK

      Connectors are properly connected.

    Result: 

    NG 

    CONNECT CONNECTOR 

    Result: 

    OK 

    See step  3

  3. CHECK CONNECTOR 
    1. Disconnect the connectors from the occupant classification ECU and front seat inner belt RH.
    2. Check that the connectors (on the occupant classification ECU side and front passenger side buckle switch side) are not damaged (Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE [08/2015 - ] ).

      OK

      Connectors are not deformed or damaged.

    Result: 

    NG 

    REPLACE FRONT SEAT WIRE RH 

    (Refer to DISASSEMBLY [08/2015 - 08/2021] )

    Result: 

    OK 

    See step  4

  4. CHECK FRONT SEAT WIRE RH (FRONT SEAT INNER BELT RH - OCCUPANT CLASSIFICATION ECU) 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
      GTY670355Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      a4-9 (BSW) - Body ground Engine switch on (IG) Below 1 V
      a4-5 (BGND) - Body ground
    3. Turn the engine switch off.
    4. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    5. Using a service wire, connect terminals 1 (RBE+) and 2 (RBE-) of connector C.
      NOTE:

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

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      a4-9 (BSW) - a4-5 (BGND) Always Below 1 Ω
    7. Disconnect the service wire from connector C.
    8. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      a4-9 (BSW) - Body ground Always 1 MΩ or higher
      a4-5 (BGND) - Body ground
      a4-9 (BSW) - a4-5 (BGND)
      TEXT IN ILLUSTRATION

      *1 Front Seat Wire RH
      *2 Front Seat Inner Belt RH
      *3 Occupant Classification ECU
      *4 Service Wire
      *5 Connector C
      *6 Connector B
      *a Front view of wire harness connector
      (to Front Seat Inner Belt RH)
      *b Front view of wire harness connector
      (to Occupant Classification ECU)

    Result: 

    NG 

    REPLACE FRONT SEAT WIRE RH 

    (Refer to DISASSEMBLY [08/2015 - 08/2021] )

    Result: 

    OK 

    See step  5

  5. CHECK FOR DTC 
    1. Connect the connectors to the occupant classification ECU and front seat inner belt RH.
    2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    3. Turn the engine switch on (IG), and wait for at least 60 seconds.
    4. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      HINT: 

      First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.

    5. Turn the engine switch off.
    6. Turn the engine switch on (IG), and wait for at least 60 seconds.
    7. Check for DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      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.

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK 

    (Refer to DIAGNOSIS SYSTEM [08/2015 - ] )

    Result: 

    NG 

    See step  6

  6. REPLACE FRONT SEAT INNER BELT ASSEMBLY RH 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Replace the front seat inner belt RH (Refer to REMOVAL [08/2015 - ] ).

      HINT: 

      Perform the inspection using parts from a normal vehicle when possible.

    4. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    5. Turn the engine switch on (IG), and wait for at least 60 seconds.
    6. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      HINT: 

      First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.

    7. Turn the engine switch off.
    8. Turn the engine switch on (IG), and wait for at least 60 seconds.
    9. Check for DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      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.

    Result: 

    OK 

    END (FRONT SEAT INNER BELT RH IS DEFECTIVE) 

    Result: 

    NG 

    See step  7

  7. REPLACE OCCUPANT CLASSIFICATION ECU 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Replace the occupant classification ECU (Refer to REMOVAL [08/2015 - ] ).

      HINT: 

      Perform the inspection using parts from a normal vehicle when possible.

    4. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    5. Turn the engine switch on (IG), and wait for at least 60 seconds.
    6. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      HINT: 

      If the DTCs are not cleared at this time, past DTCs will remain.

    Result: 

    NEXT 

    See step  8

  8. PERFORM ZERO POINT CALIBRATION 
    1. Perform the zero point calibration (Refer to INITIALIZATION [08/2015 - ] ).

      OK

      "Zero Point Calibration is complete." is displayed.

    Result: 

    NEXT 

    See step  9

  9. PERFORM SENSITIVITY CHECK 
    1. Perform the sensitivity check (Refer to INITIALIZATION [08/2015 - ] ).

      Standard

      27 to 33 kg (59.5 to 72.8 lb)

    Result: 

    NEXT 

    END (OCCUPANT CLASSIFICATION ECU IS DEFECTIVE) 

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