LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 2017 >> Corolla LE >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Occupant Classification System - Diagnostic Codes & Symptom Tests (Model Code: ZRE172) >> Occupant Classification System >> DTC B1771: Passenger Side Buckle Switch Circuit Malfunction [08/2013 - 08/2016] >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC B1771: Passenger Side Buckle Switch Circuit Malfunction [08/2013 - 08/2016]: Procedure

  1. CHECK CONNECTORS 
    1. Turn the ignition switch off.
    2. Disconnect the cable from the negative (-) 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 damaged.

      OK

      The terminals are not deformed or damaged.

      Result

      Proceed to
      OK
      NG

    Result:  2

    NG 

    REPLACE FRONT SEAT WIRE RH 

    Result:  1

    OK 

    See step  2

  2. CHECK FRONT SEAT WIRE RH (SHORT TO B+) 
    1. Connect the cable to the negative (-) battery terminal.
      GTY438385Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Inner Belt Assembly RH
      *2 Occupant Detection ECU
      *3 Front Seat Wire RH
      *a Front view of wire harness connector
      (to Occupant Detection ECU)
    2. Turn the ignition switch to ON.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      S2-8 (BSW) - Body ground Ignition switch ON Below 1 V
      S2-5 (BGND) - Body ground Ignition switch ON Below 1 V
    4. Turn the ignition switch off.
    5. Disconnect the cable from the negative (-) battery terminal.

      Result

      Proceed to
      OK
      NG

    Result:  2

    NG 

    REPLACE FRONT SEAT WIRE RH 

    Result:  1

    OK 

    See step  3

  3. CHECK FRONT SEAT WIRE RH (OPEN) 
    1. for TMMMS Made:

      Using a service wire, connect terminals 1 (+) and 2 (-) of connector C.

      NOTE:

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

    2. for TMMC Made:

      Using a service wire, connect terminals 6 (RBE+) and 2 (RBE-) of connector C.

      NOTE:

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

      GTY480048Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *A for TMMMS Made *B for TMMC Made
      *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 Front Seat Inner Belt Assembly RH)      		 *b Front view of wire harness connector
      (to Occupant Detection ECU)
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      S2-8 (BSW) - S2-5 (BGND) Always Below 1 Ω
    4. Disconnect the service wire from connector C.

      Result

      Proceed to
      OK
      NG

    Result:  2

    NG 

    REPLACE FRONT SEAT WIRE RH 

    Result:  1

    OK 

    See step  4

  4. CHECK FRONT SEAT WIRE RH (SHORT) 
    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      S2-8 (BSW) - S2-5 (BGND) Always 1 MΩ or higher
      GTY438385Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Inner Belt Assembly RH
      *2 Occupant Detection ECU
      *3 Front Seat Wire RH
      *a Front view of wire harness connector
      (to Occupant Detection ECU)

      Result

      Proceed to
      OK
      NG

    Result:  2

    NG 

    REPLACE FRONT SEAT WIRE RH 

    Result:  1

    OK 

    See step  5

  5. CHECK FRONT SEAT WIRE RH (SHORT TO GROUND) 
    1. Measure the resistance according to the value(s) in the table below.
      GTY438385Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Inner Belt Assembly RH
      *2 Occupant Detection ECU
      *3 Front Seat Wire RH
      *a Front view of wire harness connector
      (to Occupant Detection ECU)

      Standard Resistance

      Tester Connection Condition Specified Condition
      S2-8 (BSW) - Body ground Always 1 MΩ or higher
      S2-5 (BGND) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result:  2

    NG 

    REPLACE FRONT SEAT WIRE RH 

    Result:  1

    OK 

    See step  6

  6. 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 (-) battery terminal.
    3. Clear the DTCs stored in the occupant detection ECU.

      Refer to DTC CHECK / CLEAR [08/2013 - ]

      Body Electrical > Occupant Detection > Clear DTCs 

    4. Clear the DTCs stored in the airbag sensor assembly.

      Refer to DTC CHECK / CLEAR [08/2013 - ]

      Body Electrical > SRS Airbag > Clear DTCs 

    5. Turn the ignition switch off.
    6. Turn the ignition switch to ON, and wait for at least 10 seconds.
    7. Check for DTCs.

      Refer to DTC CHECK / CLEAR [08/2013 - ]

      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.

    8. Turn the ignition switch off.

      Result

      Proceed to
      OK
      NG

    Result:  1

    OK 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [08/2013 - 04/2014]  Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [04/2014 - 08/2016] 

    Result:  2

    NG 

    See step  7

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

      Refer to REMOVAL [08/2013 - 04/2014] Refer to REMOVAL [04/2014 - 08/2014] Refer to REMOVAL [08/2014 - 08/2016]

      HINT: 

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

    3. Connect the cable to the negative (-) battery terminal.
    4. Clear the DTCs stored in the occupant detection ECU.

      Refer to DTC CHECK / CLEAR [08/2013 - ]

      Body Electrical > Occupant Detection > Clear DTCs 

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

      Refer to DTC CHECK / CLEAR [08/2013 - ]

      Body Electrical > SRS Airbag > Clear DTCs 

    6. Turn the ignition switch off.
    7. Turn the ignition switch to ON, and wait for at least 10 seconds.
    8. Check for DTCs.

      Refer to DTC CHECK / CLEAR [08/2013 - ]

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

      Refer to REMOVAL [08/2013 - 04/2014] Refer to REMOVAL [04/2014 - 08/2014] Refer to REMOVAL [08/2014 - 08/2016]

      Result

      Proceed to
      OK
      NG

    Result:  1

    OK 

    REPLACE FRONT SEAT INNER BELT ASSEMBLY RH. Refer to  REMOVAL [08/2013 - 04/2014]  Refer to  REMOVAL [04/2014 - 08/2014]  Refer to  REMOVAL [08/2014 - 08/2016] 

    Result:  2

    NG 

    See step  8

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

      Refer to REMOVAL [08/2013 - ]

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

      Result

      Proceed to
      NEXT

    Result:  1

    NEXT 

    See step  9

  9. PERFORM ZERO POINT CALIBRATION AND SENSITIVITY CHECK 
    1. Using the Techstream, perform Zero Point Calibration and Sensitivity Check.

      Refer to INITIALIZATION [08/2013 - 08/2016]

      Body Electrical > Occupant Detection > Utility 

      Tester Display
      Zero Point Calibration & Sensitivity Check

      Result

      Proceed to
      NEXT

    Result:  1

    NEXT 

    END 

scientia non olet · About LEMON Manuals