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Home >> Lexus >> 2012 >> CT 200h F Sport >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Airbag System (Diagnostic Codes (B1650/32 - B1905/74) & Symptom Tests) >> Airbag System >> DTC B1656/38: Seat Belt Buckle Switch LH Circuit Malfunction >> Procedure

DTC B1656/38: Seat Belt Buckle Switch LH Circuit Malfunction: Procedure

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

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary 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 connected securely, 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 damaged.

      OK

      The terminals are not deformed or damaged.

    NG → REPLACE FLOOR WIRE 

    OK: Go to next step 

  2. CHECK FLOOR WIRE (OPEN) 
    1. Using SST, connect terminals 11 (LBE+) and 12 (LBE-) of connector B.
      Fig 1: Identifying P1 And P3 Connector Terminals
      GTY358803Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      NOTE:

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

      • SST: 09843-18040 
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      P3-2 (LBE+) - P3-1 (LBE-) Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *1 Front Seat Inner Belt Assembly LH *2 Airbag Sensor Assembly
      *3 Floor Wire *4 Connector B
      *5 Connector C - -
      *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)

    NG → REPLACE FLOOR WIRE 

    OK: Go to next step 

  3. CHECK FLOOR WIRE (SHORT) 
    1. Disconnect SST from connector B.
      Fig 2: Identifying P3 Connector Terminals
      GTY352334Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      P3-2 (LBE+) - P3-1 (LBE-) Always 1 MΩ or higher
      TEXT IN ILLUSTRATION

      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag Sensor Assembly
      *3 Floor Wire
      *4 Connector C
      *a Front view of wire harness connector
      (to Front Seat Inner Belt Assembly LH)

    NG → REPLACE FLOOR WIRE 

    OK: Go to next step 

  4. CHECK FLOOR WIRE (SHORT TO B+) 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
      Fig 3: Identifying P3 Connector Terminals
      GTY352334Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Turn the power switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      P3-2 (LBE+) - Body ground Power switch on (IG) Below 1 V
      P3-1 (LBE-) - Body ground Power switch on (IG) Below 1 V
      TEXT IN ILLUSTRATION

      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag Sensor Assembly
      *3 Floor Wire
      *4 Connector C
      *a Front view of wire harness connector
      (to Front Seat Inner Belt Assembly LH)

    NG → REPLACE FLOOR WIRE 

    OK: Go to next step 

  5. CHECK FLOOR WIRE (SHORT TO GROUND) 
    1. Turn the power switch off.
      Fig 4: Identifying P3 Connector Terminals
      GTY352334Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

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

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      P3-2 (LBE+) - Body ground Always 1 MΩ or higher
      P3-1 (LBE-) - Body ground Always 1 MΩ or higher
      TEXT IN ILLUSTRATION

      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag Sensor Assembly
      *3 Floor Wire
      *4 Connector C
      *a Front view of wire harness connector
      (to Front Seat Inner Belt Assembly LH)

    NG → REPLACE FLOOR WIRE 

    OK: Go to next step 

  6. CHECK FRONT SEAT INNER BELT ASSEMBLY LH 
    1. Connect the connectors to the airbag sensor assembly and front seat inner belt assembly LH.
      Fig 5: Identifying Side Airbag Sensor LH (For Rear Side)
      GTY244367Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Connect the cable to the negative (-) auxiliary battery terminal.
    3. Turn the power switch on (IG), and wait for at least 60 seconds.
    4. Clear the DTCs stored in memory. Refer to DTC CHECK / CLEAR .
    5. Turn the power switch off.
    6. Turn the power switch on (IG), and wait for at least 60 seconds.
    7. Check for DTCs. Refer to DTC CHECK / CLEAR .

      OK

      DTC B1656/38 is not output.

      TEXT IN ILLUSTRATION

      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag Sensor Assembly

      HINT: 

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

    NG → See step   7 

    OK → See step   9 

  7. REPLACE FRONT SEAT INNER BELT ASSEMBLY LH 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

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

    3. Replace the front seat inner belt assembly LH with a known good one. Refer to REMOVAL for Manual seat. Refer to REMOVAL for Power seat).

      HINT: 

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

    NEXT: Go to next step 

  8. CHECK AIRBAG SENSOR ASSEMBLY 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
      Fig 6: Identifying Side Airbag Sensor LH (For Rear Side)
      GTY244367Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Turn the power switch on (IG), and wait for at least 60 seconds.
    3. Clear the DTCs stored in memory. Refer to DTC CHECK / CLEAR .
    4. Turn the power switch off.
    5. Turn the power switch on (IG), and wait for at least 60 seconds.
    6. Check for DTCs. Refer to DTC CHECK / CLEAR .

      OK

      DTC B1656/38 is not output.

      TEXT IN ILLUSTRATION

      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag Sensor Assembly

      HINT: 

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

    NG → See step   10 

    OK → END 

  9. USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING 
  10. REPLACE AIRBAG SENSOR ASSEMBLY. Refer to  REMOVAL 
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