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Home >> Toyota >> 2013 >> Prius Plug-in >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Supplemental Restraint System (Diagnostic Codes (B1000/31 - B1905/74) & Symptom Tests)) (Plug-In) >> 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 ECU 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 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.

    NG → REPLACE FLOOR WIRE 

    OK: Go to next step 

  2. CHECK FLOOR WIRE (OPEN) 
    1. Using a service wire, connect terminals 11 (LBE+) and 12 (LBE-) of connector B.
      Fig 1: Checking Floor Wire For Open
      GTY343078Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      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
      R4-2 (LBE+) - R4-1 (LBE-) Always Below 1 Ω
    3. Disconnect the service wire from connector B.
      TEXT IN ILLUSTRATION

      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 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)

    NG → REPLACE FLOOR WIRE 

    OK: Go to next step 

  3. CHECK FLOOR WIRE (SHORT) 
    Fig 2: Checking Floor Wire For Short To ground
    GTY340822Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      R4-2 (LBE+) - R4-1 (LBE-) Always 1 MΩ or higher
      TEXT IN ILLUSTRATION

      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 Floor Wire
      *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: Checking Floor Wire For Short To ground
      GTY340822Courtesy 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 Condition Specified Condition
      R4-2 (LBE+) - Body ground Power switch on (IG) Below 1 V
      R4-1 (LBE-) - Body ground Power switch on (IG) Below 1 V
    4. Turn the power switch off.
    5. 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.

      TEXT IN ILLUSTRATION

      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 Floor Wire
      *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. Measure the resistance according to the value(s) in the table below.
      Fig 4: Checking Floor Wire For Short To ground
      GTY340822Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Condition Specified Condition
      R4-2 (LBE+) - Body ground Always 1 MΩ or higher
      R4-1 (LBE-) - Body ground Always 1 MΩ or higher
      TEXT IN ILLUSTRATION

      *1 Front Seat Inner Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 Floor Wire
      *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 DTC 
    1. Connect the connectors to the airbag ECU assembly and front seat inner belt assembly LH.
      Fig 5: Identifying Side Airbag Sensor Assembly Connector
      GTY315873Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Connect the cable to the negative (-) auxiliary battery terminal.
    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.

      HINT: 

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

      TEXT IN ILLUSTRATION

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

    NG → See step   7 

    OK → See step   8 

  7. CHECK FRONT SEAT INNER BELT ASSEMBLY LH 
    1. Turn the power switch off.
      Fig 6: Identifying Side Airbag Sensor Assembly Connector
      GTY315873Courtesy 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. Replace the front seat inner belt assembly LH with a known good one. Refer to REMOVAL .

      HINT: 

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

    4. Connect the cable to the negative (-) auxiliary battery terminal.
    5. Clear the DTCs stored in memory. Refer to DTC CHECK / CLEAR .
    6. Turn the power switch off.
    7. Turn the power switch on (IG), and wait for at least 60 seconds.
    8. Check for DTCs. Refer to DTC CHECK / CLEAR .

      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 power switch off.
    10. Disconnect the cable from the negative (-) auxiliary battery terminal.
    11. Return the front seat inner belt assembly LH that was installed for testing to its original location. Refer to REMOVAL .
      TEXT IN ILLUSTRATION

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

    NG → See step   9 

    OK → See step   10 

  8. USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING 
  9. REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL 
  10. REPLACE FRONT SEAT INNER BELT ASSEMBLY LH. Refer to  REMOVAL 
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