OCCUPANT CLASSIFICATION SYSTEM, Diagnostic DTC:B1771

DTC Code DTC Name
B1771 Passenger Side Buckle Switch Circuit Malfunction

DESCRIPTION

The passenger side buckle switch circuit consists of the occupant detection ECU and passenger side buckle switch (front seat inner belt assembly RH).

DTC B1771 is stored when a malfunction is detected in the passenger side buckle switch circuit.

DTC No. Detection Item DTC Detection Condition Trouble Area
B1771 Passenger Side Buckle Switch Circuit Malfunction

  • The occupant detection ECU detects a line short, short to ground or B+, or an open in the passenger side buckle switch circuit.

  • Passenger side buckle switch malfunction

  • Occupant detection ECU malfunction

  • Passenger side buckle switch (Front seat inner belt assembly RH)

  • Occupant detection ECU

WIRING DIAGRAM

B007XC8E01
*1 BSW
*2 Passenger Side Buckle Switch
*3 Front Seat Inner Belt Assembly RH
*4 Occupant Detection ECU

CAUTION / NOTICE / HINT

Note

After turning the engine switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.

Click here

Tech Tips


  • When DTC B1650/32 is stored as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant detection ECU. When DTC B1771 is output, perform troubleshooting for this DTC first.

  • If it is difficult to perform troubleshooting (wire harness inspection), remove the front passenger seat installation bolts to see under the seat cushion.

  • In the above case, lift and hold the seat so that it does not fall down. Hold the seat only as necessary because holding the seat for a long period of time may cause seat rail deformation.

PROCEDURE


  1. CHECK CONNECTORS


    1. Turn the engine switch off.

    2. Disconnect the cable from the negative (-) battery terminal.

    3. Check that the connector is properly connected to the occupant detection ECU.

      OK
      The connector is properly connected.

      Tech Tips

      If the connector is not properly connected, reconnect the connector and proceed to the next inspection.

    4. Disconnect the connector from the occupant detection ECU.

    5. Check that the terminals of the connector are not deformed or damaged.

      OK
      The terminals are not deformed or damaged.
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE FRONT SEAT INNER BELT ASSEMBLY RH Click here

    OK

  2. CHECK DTC


    1. Connect the connector to the occupant detection ECU.

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

    3. Clear the DTCs stored in the occupant detection ECU.

      Click here


      Body Electrical > Occupant Detection > Clear DTCs

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

      Click here


      Body Electrical > SRS Airbag > Clear DTCs

    5. Turn the engine switch off.

    6. Turn the engine switch on (IG), and wait for at least 10 seconds.

    7. Check for DTCs.

      Click here


      Body Electrical > Occupant Detection > Trouble Codes
      OK
      DTC B1771 is not output.

      Tech Tips

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

    8. Turn the engine switch off.

      Result
      Proceed to
      OK
      NG

    OK

    USE SIMULATION METHOD TO CHECK Click here

    NG

  3. 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.

      Click here

      Tech Tips

      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.

      Click here


      Body Electrical > Occupant Detection > Clear DTCs

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

      Click here


      Body Electrical > SRS Airbag > Clear DTCs

    6. Turn the engine switch off.

    7. Turn the engine switch on (IG), and wait for at least 10 seconds.

    8. Check for DTCs.

      Click here


      Body Electrical > Occupant Detection > Trouble Codes
      OK
      DTC B1771 is not output.

      Tech Tips

      Codes other than DTC B1771 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.

    11. Restore the front seat inner belt assembly RH that was installed for testing to its original location.

      Click here

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE FRONT SEAT INNER BELT ASSEMBLY RH Click here

    NG

  4. REPLACE OCCUPANT DETECTION ECU


    1. Turn the engine switch off.

    2. Disconnect the cable from the negative (-) battery terminal.

    3. Replace the occupant detection ECU with a new one.

      Click here

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

      Result
      Proceed to
      NEXT

    NEXT

  5. PERFORM ZERO POINT CALIBRATION


    1. Using the GTS, perform Zero Point Calibration.

      Click here


      Body Electrical > Occupant Detection > Utility
      Tester Display
      Zero Point Calibration
      Result
      Proceed to
      NEXT

    NEXT

    END