AIRBAG SYSTEM, Diagnostic DTC:B1656/38

DTC Code DTC Name
B1656/38 Seat Belt Buckle Switch LH Circuit Malfunction

DESCRIPTION

The seat belt buckle switch LH circuit consists of the airbag ECU assembly and front seat inner belt assembly LH.

DTC B1656/38 is stored when a malfunction is detected in the seat belt buckle switch LH circuit.

DTC No. Detection Item DTC Detection Condition Trouble Area
B1656/38 Seat Belt Buckle Switch LH Circuit Malfunction

    One of the following conditions is met:

  • The airbag ECU assembly detects a line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in the seat belt buckle switch LH circuit for 2 seconds.

  • A front seat inner belt assembly LH malfunction.

  • An airbag ECU assembly malfunction.

  • No. 2 floor wire

  • Front seat inner belt assembly LH

  • Airbag ECU assembly

WIRING DIAGRAM

B00598RE33

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

  • When disconnecting the cable from the negative (-) battery terminal while performing repairs, some systems need to be initialized after the cable is reconnected.

    Click here

  • After replacing the airbag ECU assembly, refer to initialization.

    Click here

PROCEDURE


  1. CHECK VEHICLE CONDITION


    1. Check vehicle condition.

      Result
      Proceed to
      for LHD
      for RHD

    for RHD

    CHECK CONNECTION OF CONNECTORS Click here

    for LHD

  2. CHECK CONNECTION OF CONNECTORS


    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 airbag ECU assembly and front seat inner belt assembly LH.

      Result
      Proceed to
      Connectors are properly connected
      Connectors are not properly connected

    Connectors are not properly connected

    CONNECT CONNECTORS PROPERLY

    Connectors are properly connected

  3. CHECK CONNECTORS


    1. B005AHGC08
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 No. 2 Floor Wire

      Disconnect the connectors from the airbag ECU assembly and front seat inner belt assembly LH.

    2. Check that the connectors (on the airbag ECU assembly side and front seat inner belt assembly LH side) are not damaged.

      Result
      Proceed to
      Connectors are not deformed or damaged
      Connectors are deformed or damaged

    Connectors are deformed or damaged

    REPLACE NO. 2 FLOOR WIRE

    Connectors are not deformed or damaged

  4. CHECK NO. 2 FLOOR WIRE


    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

      B00576DC04
      *1 Front Seat Inner Belt Assembly LH *2 Airbag ECU Assembly
      *3 No. 2 Floor Wire *4 Connector C
      *5 Connector B *6 Service Wire
      *a

      Front view of wire harness connector

      (to Front Seat Inner Belt Assembly LH)

      		 *b

      Rear view of wire harness connector

      (to Airbag ECU Assembly)

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      Q45-2 (LBE+) - Body ground Engine switch on (IG) Below 1 V
      Q45-1 (LBE-) - Body ground Engine switch on (IG) Below 1 V

    4. Turn the engine switch off.

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

    6. Using a service wire, connect terminals 15 (LBE+) and 23 (LBE-) of connector B.

      Note

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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Q45-2 (LBE+) - Q45-1 (LBE-) Always Below 1 Ω

    8. Disconnect the service wire from connector B.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Q45-2 (LBE+) - Q45-1 (LBE-) Always 1 MΩ or higher
      Q45-2 (LBE+) - Body ground Always 1 MΩ or higher
      Q45-1 (LBE-) - Body ground Always 1 MΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE NO. 2 FLOOR WIRE

    OK

  5. CHECK DTC


    1. B005991C09
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly

      Connect the connectors to the airbag ECU assembly and front seat inner belt assembly LH.

    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.

      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 60 seconds.

    7. Check for DTCs.

      Click here


      Body Electrical > SRS Airbag > Trouble Codes
      Result
      Proceed to
      DTC B1656/38 is not output
      DTC B1656/38 is output

      Tech Tips

      Codes other than DTC B1656/38 may be output at this time, but they are not related to this check.


    DTC B1656/38 is not output

    USE SIMULATION METHOD TO CHECK Click here

    DTC B1656/38 is output

  6. REPLACE FRONT SEAT INNER BELT ASSEMBLY LH


    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 assembly LH.

      for Manual Seat: Click here

      for Power Seat: Click here

      Tech Tips

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

      Result
      Proceed to
      NEXT

    NEXT

  7. CHECK DTC


    1. B005991C09
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly

      Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

    2. Turn the engine switch on (IG), and wait for at least 60 seconds.

    3. Clear the DTCs.

      Click here


      Body Electrical > SRS Airbag > Clear DTCs

    4. Turn the engine switch off.

    5. Turn the engine switch on (IG), and wait for at least 60 seconds.

    6. Check for DTCs.

      Click here


      Body Electrical > SRS Airbag > Trouble Codes
      Result
      Proceed to
      DTC B1656/38 is not output
      DTC B1656/38 is output

      Tech Tips

      Codes other than DTC B1656/38 may be output at this time, but they are not related to this check.


    DTC B1656/38 is not output

    END (FRONT SEAT INNER BELT ASSEMBLY LH WAS DEFECTIVE)

    DTC B1656/38 is output

    REPLACE AIRBAG ECU ASSEMBLY Click here

  8. CHECK CONNECTION OF CONNECTORS


    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 airbag ECU assembly and front seat inner belt assembly LH.

      Result
      Proceed to
      Connectors are properly connected
      Connectors are not properly connected

    Connectors are not properly connected

    CONNECT CONNECTORS PROPERLY

    Connectors are properly connected

  9. CHECK CONNECTORS


    1. B005AHGC08
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 No. 2 Floor Wire

      Disconnect the connectors from the airbag ECU assembly and front seat inner belt assembly LH.

    2. Check that the connectors (on the airbag ECU assembly side and front seat inner belt assembly LH side) are not damaged.

      Result
      Proceed to
      Connectors are not deformed or damaged
      Connectors are deformed or damaged

    Connectors are deformed or damaged

    REPLACE NO. 2 FLOOR WIRE

    Connectors are not deformed or damaged

  10. CHECK NO. 2 FLOOR WIRE


    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

      B005ATFC01
      *1 Front Seat Inner Belt Assembly LH *2 Airbag ECU Assembly
      *3 No. 2 Floor Wire *4 Connector C
      *5 Connector B *6 Service Wire
      *a

      Front view of wire harness connector

      (to Front Seat Inner Belt Assembly LH)

      		 *b

      Rear view of wire harness connector

      (to Airbag ECU Assembly)

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      Q13-2 (LBE+) - Body ground Engine switch on (IG) Below 1 V
      Q13-1 (LBE-) - Body ground Engine switch on (IG) Below 1 V

    4. Turn the engine switch off.

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

    6. Using a service wire, connect terminals 15 (LBE+) and 23 (LBE-) of connector B.

      Note

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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Q13-2 (LBE+) - Q13-1 (LBE-) Always Below 1 Ω

    8. Disconnect the service wire from connector B.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Q13-2 (LBE+) - Q13-1 (LBE-) Always 1 MΩ or higher
      Q13-2 (LBE+) - Body ground Always 1 MΩ or higher
      Q13-1 (LBE-) - Body ground Always 1 MΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE NO. 2 FLOOR WIRE

    OK

  11. CHECK DTC


    1. B005991C09
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly

      Connect the connectors to the airbag ECU assembly and front seat inner belt assembly LH.

    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.

      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 60 seconds.

    7. Check for DTCs.

      Click here


      Body Electrical > SRS Airbag > Trouble Codes
      Result
      Proceed to
      DTC B1656/38 is not output
      DTC B1656/38 is output

      Tech Tips

      Codes other than DTC B1656/38 may be output at this time, but they are not related to this check.


    DTC B1656/38 is not output

    USE SIMULATION METHOD TO CHECK Click here

    DTC B1656/38 is output

  12. REPLACE FRONT SEAT INNER BELT ASSEMBLY LH


    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 assembly LH.

      for Manual Seat: Click here

      for Power Seat: Click here

      Tech Tips

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

      Result
      Proceed to
      NEXT

    NEXT

  13. CHECK DTC


    1. B005991C09
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly

      Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

    2. Turn the engine switch on (IG), and wait for at least 60 seconds.

    3. Clear the DTCs.

      Click here


      Body Electrical > SRS Airbag > Clear DTCs

    4. Turn the engine switch off.

    5. Turn the engine switch on (IG), and wait for at least 60 seconds.

    6. Check for DTCs.

      Click here


      Body Electrical > SRS Airbag > Trouble Codes
      Result
      Proceed to
      DTC B1656/38 is not output
      DTC B1656/38 is output

      Tech Tips

      Codes other than DTC B1656/38 may be output at this time, but they are not related to this check.


    DTC B1656/38 is not output

    END (FRONT SEAT INNER BELT ASSEMBLY LH WAS DEFECTIVE)

    DTC B1656/38 is output

    REPLACE AIRBAG ECU ASSEMBLY Click here