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DTC B1780: Front Occupant Classification Sensor LH Circuit Malfunction [11/2018 - 02/2019]: Procedure

  1. CHECK CONNECTION OF CONNECTORS 
    1. Turn the ignition 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 occupant detection ECU and front occupant classification sensor LH.

      Result

      Proceed to
      Connectors are properly connected
      Connectors are not properly connected

    Result: 

    Connectors are not properly connected 

    CONNECT CONNECTORS PROPERLY 

    Result: 

    Connectors are properly connected 

    See step  2

  2. CHECK CONNECTORS 
    1. Disconnect the connectors from the occupant detection ECU and front occupant classification sensor LH.
    2. Check that the connectors (on the occupant detection ECU side and front occupant classification sensor LH side) are not damaged.

      Result

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

    Result: 

    Connectors are deformed or damaged 

    REPLACE FRONT SEAT WIRE RH. Refer to  DISASSEMBLY [11/2018 - 08/2020] 

    Result: 

    Connectors are not deformed or damaged 

    See step  3

  3. CHECK FRONT SEAT WIRE RH 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
      GTY887401Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Occupant Classification Sensor LH
      *2 Occupant Detection ECU
      *3 Front Seat Wire RH
      *4 Service Wire
      *a Front view of wire harness connector
      (to Occupant Detection ECU)
      *b Front view of wire harness connector
      (to Front Occupant Classification Sensor LH)
    2. Turn the ignition switch to ON.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      S22-1 - Body ground Ignition switch ON Below 1 V
      S22-3 - Body ground
      S22-5 - Body ground
    4. Turn the ignition switch off.
    5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    6. Using service wires, connect terminals 1 (SVC) and 3 (SGD), and terminals 2 (SIG) and 3 (SGD) of connector C.
      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
      S22-1 - S22-5 Always Below 1 Ω
      S22-3 - S22-5
    8. Disconnect the service wire from connector C.
    9. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      S22-1 - S22-5 Always 1 MΩ or higher
      S22-3 - S22-5
      S22-1 - S22-3
      S22-1 - Body ground
      S22-3 - Body ground
      S22-5 - Body ground

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FRONT SEAT WIRE RH. Refer to  DISASSEMBLY [11/2018 - 08/2020] 

    Result: 

    OK 

    See step  4

  4. CHECK DTC 
    1. Connect the connectors to the occupant detection ECU and front occupant classification sensor LH.
    2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    3. Turn the ignition switch to ON, and wait for at least 60 seconds.
    4. Clear the DTCs stored in the occupant detection ECU.

      Refer to DTC CHECK / CLEAR [11/2018 - ]

      Body Electrical > Occupant Detection > Clear DTCs 

    5. Clear the DTCs stored in the airbag ECU assembly.

      Refer to DTC CHECK / CLEAR [11/2018 - ]

      Body Electrical > SRS Airbag > Clear DTCs 

    6. Turn the ignition switch off.
    7. Turn the ignition switch to ON, and wait for at least 60 seconds.
    8. Check the DTCs stored in the occupant detection ECU.

      Refer to DTC CHECK / CLEAR [11/2018 - ]

      Body Electrical > Occupant Detection > Trouble Codes 

      Result

      Proceed to
      DTC B1780 is output
      DTC B1780 is not output

      HINT: 

      Codes other than DTC B1780 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1780 is not output 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2018 - ] 

    Result: 

    DTC B1780 is output 

    See step  5

  5. CHECK OCCUPANT DETECTION ECU 
    1. Turn the ignition switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Replace the occupant detection ECU with a new one.

      Refer to DISASSEMBLY [11/2018 - 08/2020]

      HINT: 

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

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  6

  6. CHECK DTC 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    2. Turn the ignition switch to ON, and wait for at least 60 seconds.
    3. Clear the DTCs stored in the occupant detection ECU.

      Refer to DTC CHECK / CLEAR [11/2018 - ]

      Body Electrical > Occupant Detection > Clear DTCs 

    4. Clear the DTCs stored in the airbag ECU assembly.

      Refer to DTC CHECK / CLEAR [11/2018 - ]

      Body Electrical > SRS Airbag > Clear DTCs 

    5. Turn the ignition switch off.
    6. Turn the ignition switch to ON, and wait for at least 60 seconds.
    7. Check the DTCs stored in the occupant detection ECU.

      Refer to DTC CHECK / CLEAR [11/2018 - ]

      Body Electrical > Occupant Detection > Trouble Codes 

      Result

      Proceed to
      DTC B1780 is output
      DTC B1780 is not output

      HINT: 

      Codes other than DTC B1780 may be output at this time, but they are not related to this check.

    8. Turn the ignition switch off.
    9. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.

    Result: 

    DTC B1780 is not output 

    See step  9

    Result: 

    DTC B1780 is output 

    See step  7

  7. REPLACE FRONT SEAT ADJUSTER ASSEMBLY RH 
    1. Replace the front seat adjuster assembly RH with a new one.

      Refer to DISASSEMBLY [11/2018 - 08/2020]

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

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  8

  8. PERFORM ZERO POINT CALIBRATION 
    1. Using the Techstream, perform "Zero Point Calibration".

      Refer to INITIALIZATION [11/2018 - ]

      Body Electrical > Occupant Detection > Utility 

      Tester Display
      Zero Point Calibration

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    END (FRONT SEAT ADJUSTER ASSEMBLY RH WAS DEFECTIVE) 

  9. PERFORM ZERO POINT CALIBRATION 
    1. Using the Techstream, perform "Zero Point Calibration".

      Refer to INITIALIZATION [11/2018 - ]

      Body Electrical > Occupant Detection > Utility 

      Tester Display
      Zero Point Calibration

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    END (OCCUPANT DETECTION ECU WAS DEFECTIVE) 

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