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 classification ECU and front seat inner belt assembly RH.

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

Troubleshoot DTC B1771 first if DTCs B1771 and B1795 are output simultaneously.

DTC No. DTC Detection Condition Trouble Area
B1771

  • The occupant classification ECU receives a line short circuit signal, an open circuit signal, a short circuit to ground signal or a short circuit to B+ signal in the passenger side buckle switch circuit for 2 seconds.

  • Passenger side buckle switch malfunction

  • Occupant classification ECU malfunction

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

  • Occupant classification ECU

  • Front seat wire RH

Tech Tips

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

WIRING DIAGRAM

A01EKMNE01

INSPECTION PROCEDURE

Tech Tips


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

  • In the above case, 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 ignition switch off.

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

    3. Check that the connectors are properly connected to the occupant classification ECU and front seat inner belt assembly RH.

      OK
      The connectors are properly connected.

      Tech Tips

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

    4. Disconnect the connectors from the occupant classification ECU and front seat inner belt assembly RH.

    5. Check that the terminals of connectors are not damaged.

      OK
      The terminals are not deformed or damaged.

    NG

    REPLACE FRONT SEAT WIRE RH

    OK

  2. CHECK FRONT SEAT WIRE RH (SHORT TO B+)


    1. A01EJ87E10
      Text in Illustration
      *1 Front Seat Inner Belt Assembly RH
      *2 Occupant Classification ECU
      *3 Front Seat Wire RH
      *4

      Front view of wire harness connector

      (to Occupant Classification ECU)
      *5 Connector B

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

    2. Turn the ignition switch to ON.

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      S12-9 (BSW) - Body ground Ignition switch ON Below 1 V
      S12-5 (BGND) - Body ground Ignition switch ON Below 1 V

    NG

    REPLACE FRONT SEAT WIRE RH

    OK

  3. CHECK FRONT SEAT WIRE RH (OPEN)


    1. Turn the ignition switch off.

      A01EJX5E10

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

    3. Using SST, connect terminals 2 and 1 of connector C.

      Note

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

      SST
      09843-18040

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      S12-9 (BSW) - S12-5 (BGND) Always Below 1 Ω
      Text in Illustration
      *1 Front Seat Inner Belt Assembly RH *2 Occupant Classification ECU
      *3 Front Seat Wire RH *4

      Front view of wire harness connector

      (to Occupant Classification ECU)
      *5

      Front view of wire harness connector

      (to Front Seat Inner Belt Assembly RH)

      		 *6 Connector B
      *7 Connector C - -

    NG

    REPLACE FRONT SEAT WIRE RH

    OK

  4. CHECK FRONT SEAT WIRE RH (SHORT)


    1. A01EJ87E10
      Text in Illustration
      *1 Front Seat Inner Belt Assembly RH
      *2 Occupant Classification ECU
      *3 Front Seat Wire RH
      *4

      Front view of wire harness connector

      (to Occupant Classification ECU)
      *5 Connector B

      Disconnect SST from connector C.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      S12-9 (BSW) - S12-5 (BGND) Always 1 MΩ or higher

    NG

    REPLACE FRONT SEAT WIRE RH

    OK

  5. CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)


    1. A01EJ87E10
      Text in Illustration
      *1 Front Seat Inner Belt Assembly RH
      *2 Occupant Classification ECU
      *3 Front Seat Wire RH
      *4

      Front view of wire harness connector

      (to Occupant Classification ECU)
      *5 Connector B

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      S12-9 (BSW) - Body ground Always 1 MΩ or higher
      S12-5 (BGND) - Body ground Always 1 MΩ or higher

    NG

    REPLACE FRONT SEAT WIRE RH

    OK

  6. CHECK DTC


    1. Connect the connectors to the occupant classification ECU and front seat inner belt assembly RH.

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

    3. Turn the ignition switch to ON.

    4. Clear the DTCs stored in the occupant classification ECU Click here.

    5. Clear the DTCs stored in the center airbag sensor assembly Click here.

    6. Turn the ignition switch off.

    7. Turn the ignition switch to ON.

    8. Check for DTCs Click here.

      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.


    NG

    REPLACE FRONT SEAT INNER BELT ASSEMBLY RH Click here

    OK

    USE SIMULATION METHOD TO CHECK Click here

  7. REPLACE FRONT SEAT INNER BELT ASSEMBLY RH


    1. Turn the ignition switch off.

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

    3. Replace the front seat inner belt assembly RH Click here.

      Tech Tips

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

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

    5. Turn the ignition switch to ON.

    6. Clear the DTCs stored in the occupant classification ECU Click here.

    7. Clear the DTCs stored in the center airbag sensor assembly Click here.

    8. Turn the ignition switch off.

    9. Turn the ignition switch to ON.

    10. Check for DTCs Click here.

      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.


    NG

    REPLACE OCCUPANT CLASSIFICATION ECU Click here

    OK

    END

  8. REPLACE OCCUPANT CLASSIFICATION ECU


    1. Turn the ignition switch off.

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

    3. Replace the occupant classification ECU Click here.


    NEXT

  9. PERFORM ZERO POINT CALIBRATION


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

    2. Connect the GTS to the DLC3.

    3. Turn the ignition switch to ON.

    4. Using the GTS, perform Zero Point Calibration Click here.

      OK
      "Zero Point Calibration is complete." is displayed.

    NEXT

  10. PERFORM SENSITIVITY CHECK


    1. Using the GTS, perform Sensitivity Check Click here.

      Standard
      27 to 33 kg (59.5 to 72.8 lb)

    NEXT

    END