OCCUPANT CLASSIFICATION SYSTEM, Diagnostic DTC:B1771

DTC Code DTC Name
B1771 Passenger Side Buckle Switch Circuit Malfunction

DESCRIPTION

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

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

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

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B1771

Passenger Side Buckle Switch Circuit Malfunction

  • One of the following conditions is met:

  • Occupant detection ECU detects a line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to +B signal in the front passenger side buckle switch circuit for 2 seconds.

  • Front passenger side buckle switch malfunction.

  • Occupant detection ECU malfunction.

  • Front seat wire RH

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

  • Occupant detection ECU
Tip:

  • When DTC B1650/32 is stored as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1771 of the occupant classification system.

  • Use the GTS to check for DTCs of the occupant detection ECU, otherwise the DTCs cannot be read.

WIRING DIAGRAM

C253566E21

CAUTION / NOTICE / HINT

Note:

When disconnecting the cable, some systems need to be initialized after the cable is reconnected.

Click hereClick here

Tip:

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

  • In the above case, hold the seat so that it does not fall down. Holding the seat for a long period of time may cause a problem, such as seat rail deformation. Hold the seat up only for as long as necessary.

PROCEDURE

  1. CHECK DTC

    1. Turn the ignition switch to ON, and wait for at least 60 seconds.

    2. Clear the DTCs.

      Click here

      Body Electrical > Occupant Detection > Clear DTCs

      Tip:

      First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag sensor assembly.

    3. Turn the ignition switch off.

    4. Turn the ignition switch to ON, and wait for at least 60 seconds.

    5. Check for DTCs.

      Click here

      Body Electrical > Occupant Detection > Trouble Codes

      Result

      Proceed to

      DTC B1771 is not output

      DTC B1771 is output
      Tip:

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

    DTC B1771 is not output

    USE SIMULATION METHOD TO CHECK

    Click here

    DTC B1771 is output

  2. CHECK CONNECTION OF CONNECTOR

    1. Turn the ignition 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 detection ECU.

    Result

    Proceed to

    Connectors are properly connected

    Connectors are not properly connected
    Connectors are not properly connected

    CONNECT CONNECTOR

    Connectors are properly connected

  3. CHECK CONNECTORS

    1. C281859C01

      *1

      Front Seat Inner Belt Assembly RH

      *2

      Occupant Detection ECU

      *3

      Front Seat Wire RH

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

    2. Check that the connectors are not damaged.

    Result

    Proceed to

    Connectors are not deformed or damaged

    Connectors are deformed or damaged
    Connectors are deformed or damaged

    REPLACE FRONT SEAT WIRE RH

    Connectors are not deformed or damaged

  4. CHECK DTC

    1. Connect the connectors to the occupant detection 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 ignition switch to ON, and wait for at least 60 seconds.

    4. Clear the DTCs.

      Click here

      Body Electrical > Occupant Detection > Clear DTCs

      Note:

      First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag sensor assembly.

    5. Turn the ignition switch off.

    6. Turn the ignition switch to ON, and wait for at least 60 seconds.

    7. Check for DTCs.

      Click here

      Body Electrical > Occupant Detection > Trouble Codes

      Result

      Proceed to

      DTC B1771 is not output

      DTC B1771 is output
      Tip:

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

    DTC B1771 is not output

    USE SIMULATION METHOD TO CHECK

    Click here

    DTC B1771 is output

  5. CHECK FRONT SEAT WIRE RH

    1. Turn the ignition switch to ON.

      C281869C02

      *1

      Front Seat Inner Belt Assembly RH

      *2

      Occupant Detection ECU

      *3

      Front Seat Wire RH

      *4

      Connector B

      *5

      Connector C

      *6

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

      Standard Voltage

      Tester Connection

      Switch Condition

      Specified Condition

      d16-8 - Body ground

      Ignition switch to ON

      Below 1 V

      d16-5 - Body ground

    3. Turn the ignition switch off.

    4. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.

    5. Using service wires, connect terminals 1(LBE-) and 2(LBE+) of connector C.

      Note:

      Do not forcibly insert the service wires 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

      d16-8 - d16-5

      Always

      Below 1 Ω

    7. Disconnect the service wires from connector C.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      d16-8 - d16-5

      Always

      1 MΩ or higher

      d16-8 - Body ground

      d16-5 - Body ground

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE FRONT SEAT WIRE RH

    OK

  6. CHECK FRONT SEAT INNER BELT ASSEMBLY RH

    1. Turn the ignition 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.

      Click here

      Tip:

      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 ignition switch to ON, and wait for at least 60 seconds.

    6. Clear the DTCs.

      Click here

      Body Electrical > Occupant Detection > Clear DTCs

      Tip:

      First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag sensor assembly.

    7. Turn the ignition switch off.

    8. Turn the ignition switch to ON, and wait for at least 60 seconds.

    9. Check for DTCs.

      Click here

      Body Electrical > Occupant Detection > Trouble Codes

      Result

      Proceed to

      DTC B1771 is not output

      DTC B1771 is output
      Tip:

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

    DTC B1771 is not output

    END (FRONT SEAT INNER BELT ASSEMBLY RH WAS DEFECTIVE)

    DTC B1771 is output

  7. REPLACE OCCUPANT DETECTION ECU

    1. Turn the ignition switch off.

    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.

    3. Replace the occupant detection ECU.

      Click here

      Tip:

      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.

    Result

    Proceed to

    NEXT
    NEXT

  8. PERFORM ZERO POINT CALIBRATION

    1. Perform the zero point calibration.

      Click here

    Result

    Proceed to

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

  9. PERFORM SENSITIVITY CHECK

    1. Perform the sensitivity check.

      Click here

      Standard

      27 to 33 kg (59.5 to 72.8 lb)

    Result

    Proceed to

    NEXT
    NEXT

    END (OCCUPANT DETECTION ECU WAS DEFECTIVE)