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Home >> Toyota >> 2021 >> C-HR XLE >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Supplemental Restraint System - Diagnostic Codes (B1627-B1656) >> Airbag System >> DTC B1656/38: Seat Belt Buckle Switch LH Circuit Malfunction [02/2017 - 09/2019] >> Procedure

DTC B1656/38: Seat Belt Buckle Switch LH Circuit Malfunction [02/2017 - 09/2019]: Procedure

  1. CHECK CONNECTORS 
    1. Turn the ignition switch off.
    2. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

    3. Check that the connectors are properly connected to the airbag sensor assembly and front seat inner belt assembly LH.

      OK

      The connectors are properly connected.

      HINT: 

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

    4. Disconnect the connectors from the airbag sensor assembly and front seat inner belt assembly LH.
    5. Check that the terminals of the connectors are not deformed or damaged.

      OK

      The terminals are not deformed or damaged.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FLOOR WIRE 

    Result: 

    OK 

    See step  2

  2. CHECK FLOOR WIRE (OPEN) 
    1. Using a service wire, connect terminals 10 (LBE+) and 18 (LBE-) of connector B.
      GTY758113Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag Sensor Assembly
      *3 Floor Wire
      *4 Service Wire
      *a Front view of wire harness connector
      (to Airbag Sensor Assembly)
      *b Front view of wire harness connector
      (to Front Seat Inner Belt Assembly LH)
      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
      M101-2 (LBE+) - M101-1 (LBE-) Always Below 1 Ω
    3. Disconnect the service wire from connector B.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FLOOR WIRE 

    Result: 

    OK 

    See step  3

  3. CHECK FLOOR WIRE (SHORT) 
    1. Measure the resistance according to the value(s) in the table below.
      GTY761309Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag Sensor Assembly
      *3 Floor Wire
      *a Front view of wire harness connector
      (to Front Seat Inner Belt Assembly LH)

      Standard Resistance

      Tester Connection Condition Specified Condition
      M101-2 (LBE+) - M101-1 (LBE-) Always 1 MΩ or higher

      Result

      Result
      OK
      NG

    Result: 

    NG 

    REPLACE FLOOR WIRE 

    Result: 

    OK 

    See step  4

  4. CHECK FLOOR WIRE (SHORT TO B+) 
    1. Connect the cable to the negative (-) battery terminal.
      GTY761309Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag Sensor Assembly
      *3 Floor Wire
      *a Front view of wire harness connector
      (to Front Seat Inner Belt Assembly LH)
    2. Turn the ignition switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      M101-2 (LBE+) - Body ground Ignition switch on (IG) Below 1 V
      M101-1 (LBE-) - Body ground Ignition switch on (IG) Below 1 V
    4. Turn the ignition switch off.
    5. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FLOOR WIRE 

    Result: 

    OK 

    See step  5

  5. CHECK FLOOR WIRE (SHORT TO GROUND) 
    1. Measure the resistance according to the value(s) in the table below.
      GTY761309Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag Sensor Assembly
      *3 Floor Wire
      *a Front view of wire harness connector
      (to Front Seat Inner Belt Assembly LH)

      Standard Resistance

      Tester Connection Condition Specified Condition
      M101-2 (LBE+) - Body ground Always 1 MΩ or higher
      M101-1 (LBE-) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FLOOR WIRE 

    Result: 

    OK 

    See step  6

  6. CHECK DTC 
    1. Connect the connectors to the airbag sensor assembly and front seat inner belt assembly LH.
      GTY447346Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag Sensor Assembly
    2. Connect the cable to the negative (-) battery terminal.
    3. Clear the DTCs stored in memory.

      Refer to DTC CHECK / CLEAR [02/2017 - 09/2019]

      Body Electrical > SRS Airbag > Clear DTCs 

    4. Turn the ignition switch off.
    5. Turn the ignition switch on (IG), and wait for at least 60 seconds.
    6. Check for DTCs.

      Refer to DTC CHECK / CLEAR [02/2017 - 09/2019]

      Body Electrical > SRS Airbag > Trouble Codes 

      OK

      DTC B1656/38 is not output.

      HINT: 

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

      Result

      Result
      OK
      NG

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [02/2017 - 10/2017]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2017 - 05/2018]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [05/2018 - 09/2019] 

    Result: 

    NG 

    See step  7

  7. CHECK FRONT SEAT INNER BELT ASSEMBLY LH 
    1. Turn the ignition switch off.
      GTY447346Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag Sensor Assembly
    2. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

    3. Replace the front seat inner belt assembly LH with a known good one.

      Refer to REMOVAL [02/2017 - 10/2017] , or refer to REMOVAL [10/2017 - 09/2019]

      HINT: 

      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.

      Refer to DTC CHECK / CLEAR [02/2017 - 09/2019]

      Body Electrical > SRS Airbag > Clear DTCs 

    6. Turn the ignition switch off.
    7. Turn the ignition switch on (IG), and wait for at least 60 seconds.
    8. Check for DTCs.

      Refer to DTC CHECK / CLEAR [02/2017 - 09/2019]

      Body Electrical > SRS Airbag > Trouble Codes 

      OK

      DTC B1656/38 is not output.

      HINT: 

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

    9. Turn the ignition switch off.
    10. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

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

      Refer to REMOVAL [02/2017 - 10/2017] , or refer to REMOVAL [10/2017 - 09/2019]

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FRONT SEAT INNER BELT ASSEMBLY LH. Refer to  REMOVAL [02/2017 - 10/2017]  , or refer to  REMOVAL [10/2017 - 09/2019] 

    Result: 

    NG 

    REPLACE AIRBAG SENSOR ASSEMBLY. Refer to  REMOVAL [02/2017 - 10/2017]  , or refer to  REMOVAL [10/2017 - 09/2019] 

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