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 seat belt buckle switch LH (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 Test Mode / Check Mode
B1656/38 Seat Belt Buckle Switch LH Circuit Malfunction

Any of the following conditions is met:


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

  • Seat belt buckle switch LH malfunction

  • Airbag ECU assembly malfunction

  • No. 2 Floor wire

  • Seat belt buckle switch LH (Front seat inner belt assembly LH)

  • Airbag ECU assembly

 Does not apply to test/check mode
DTC Detection Conditions
Vehicle Condition
Pattern 1 Pattern 2 Pattern 3
Diagnosis Condition - - - -
Malfunction Status The airbag ECU assembly detects a line short, short to ground or B+, or an open in the seat belt buckle switch LH circuit ○ - -
Seat belt buckle switch LH malfunction - ○ -
Airbag ECU assembly malfunction - - ○
Detection Time - - -
Number of Trips 1 trip 1 trip 1 trip

Tech Tips

DTC will be output when conditions for either of the patterns in the table above are met.

WIRING DIAGRAM

B002CUXE33
*a Seat Belt Buckle Switch LH (Front Seat Inner Belt Assembly LH)
*b Airbag ECU Assembly

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 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.

      OK
      The connectors are properly connected.

      Tech Tips

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

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

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

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

    NG

    REPLACE NO. 2 FLOOR WIRE

    OK

  2. CHECK NO. 2 FLOOR WIRE (OPEN)


    1. B002DJRC06
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 No. 2 Floor Wire
      *4 Service Wire
      *a

      Front view of wire harness connector

      (to Airbag ECU Assembly)
      *b

      Front view of wire harness connector

      (to Front Seat Inner Belt Assembly LH)

      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 the wire.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      U2-2 (LBE+) - U2-1 (LBE-) Always Below 1 Ω

    3. Disconnect the service wire from connector B.

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE NO. 2 FLOOR WIRE

    OK

  3. CHECK NO. 2 FLOOR WIRE (SHORT)


    1. B002EK9C07
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 No. 2 Floor Wire
      *a

      Front view of wire harness connector

      (to Front Seat Inner Belt Assembly LH)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      U2-2 (LBE+) - U2-1 (LBE-) Always 1 MΩ or higher
      Result
      Result
      OK
      NG

    NG

    REPLACE NO. 2 FLOOR WIRE

    OK

  4. CHECK NO. 2 FLOOR WIRE (SHORT TO B+)


    1. B002EK9C07
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 No. 2 Floor Wire
      *a

      Front view of wire harness connector

      (to Front Seat Inner Belt Assembly LH)

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

    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
      U2-2 (LBE+) - Body ground Engine switch on (IG) Below 1 V
      U2-1 (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.

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE NO. 2 FLOOR WIRE

    OK

  5. CHECK NO. 2 FLOOR WIRE (SHORT TO GROUND)


    1. B002EK9C07
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 No. 2 Floor Wire
      *a

      Front view of wire harness connector

      (to Front Seat Inner Belt Assembly LH)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      U2-2 (LBE+) - Body ground Always 1 MΩ or higher
      U2-1 (LBE-) - Body ground Always 1 MΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE NO. 2 FLOOR WIRE

    OK

  6. CHECK DTC


    1. B002EJAC10
      *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.

    3. Clear the DTCs stored in memory.

      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
      OK
      DTC B1656/38 is not output.

      Tech Tips

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

      Result
      Result
      OK
      NG

    OK

    USE SIMULATION METHOD TO CHECK Click here

    NG

  7. CHECK FRONT SEAT INNER BELT ASSEMBLY LH


    1. B002EJAC10
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly

      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 with a known good one.

      Click here

      Tech Tips

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

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

    5. Clear the DTCs stored in memory.

      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 60 seconds.

    8. Check for DTCs.

      Click here


      Body Electrical > SRS Airbag > Trouble Codes
      OK
      DTC B1656/38 is not output.

      Tech Tips

      Codes other than DTC B1656/38 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, and wait for at least 90 seconds.

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

      Click here

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE FRONT SEAT INNER BELT ASSEMBLY LH Click here

    NG

    REPLACE AIRBAG ECU ASSEMBLY Click here