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OCCUPANT CLASSIFICATION SYSTEM, Diagnostic DTC:B1780

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DTC Code DTC Name
B1780 Front Occupant Classification Sensor LH Circuit Malfunction
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DESCRIPTION

The front occupant classification sensor LH circuit consists of the occupant detection ECU and front occupant classification sensor LH.

DTC B1780 is stored when a malfunction is detected in the front occupant classification sensor LH circuit.

DTC No. Detection Item DTC Detection Condition Trouble Area
B1780 Front Occupant Classification Sensor LH Circuit Malfunction

  • The occupant detection ECU detects a line short, short to ground or B+, or an open in the front occupant classification sensor LH circuit.

  • Front occupant classification sensor LH malfunction

  • Occupant detection ECU malfunction

  • Front seat wire RH

  • Front seat adjuster assembly RH (Front occupant classification sensor LH)*

  • Occupant detection ECU

Table 1. *a Front Seat Adjuster Assembly RH (Front Occupant Classification Sensor LH) *b Occupant Detection ECU
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WIRING DIAGRAM

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CAUTION / NOTICE / HINT

Note:

After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

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Tip:

  • When DTC B1650 is stored as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant detection ECU. When DTC B1780 is output, perform troubleshooting for this DTC first.

  • If it is difficult to perform troubleshooting (wire harness inspection), remove the front passenger seat installation bolts to see under the seat cushion.

  • In the above case, lift and hold the seat so that it does not fall down. Hold the seat only as necessary because holding the seat for a long period of time may cause seat rail deformation.

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PROCEDURE


  1. Click here

    CHECK CONNECTORS


    1. Turn the power switch off.

    2. Disconnect the cable from the negative (-) auxiliary battery terminal.

    3. Check that the connectors are properly connected to the occupant detection ECU and front occupant classification sensor LH.

      OK
      The connectors are properly connected.
      Tip:

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

    4. Disconnect the connectors from the occupant detection ECU and front occupant classification sensor 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

  2. Click here

    CHECK FRONT SEAT WIRE RH


    1. B004S22C19
      *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)

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

    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
      Q42-1 (SVC1) - Body ground Power switch on (IG) Below 1 V
      Q42-3 (SIG1) - Body ground
      Q42-5 (SGD1) - Body ground

    4. Turn the power switch off.

    5. Disconnect the cable from the negative (-) auxiliary battery terminal.

    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 the wire.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Q42-1 (SVC1) - Q42-5 (SGD1) Always Below 1 Ω
      Q42-3 (SIG1) - Q42-5 (SGD1)

    8. Disconnect the service wires from connector C.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Q42-1 (SVC1) - Q42-5 (SGD1) Always 1 MΩ or higher
      Q42-3 (SIG1) - Q42-5 (SGD1)
      Q42-1 (SVC1) - Q42-3 (SIG1)
      Q42-1 (SVC1) - Body ground
      Q42-3 (SIG1) - Body ground
      Q42-5 (SGD1) - Body ground
      Result
      Proceed to
      OK
      NG

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    CHECK DTC


    1. Connect the connectors to the occupant detection ECU and front occupant classification sensor LH.

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

    3. Clear the DTCs stored in the occupant detection ECU.

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      1. Body Electrical > Occupant Detection > Clear DTCs


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


      1. Body Electrical > SRS Airbag > Clear DTCs


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    5. Turn the power switch off.

    6. Turn the power switch on (IG), and wait for at least 10 seconds.

    7. Check for DTCs.

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      1. Body Electrical > Occupant Detection > Trouble Codes


      OK
      DTC B1780 is not output.
      Tip:

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

    8. Turn the power switch off.

      Result
      Proceed to
      OK
      NG

  4. Click here

    CHECK OCCUPANT DETECTION ECU


    1. Disconnect the cable from the negative (-) auxiliary battery terminal.

    2. Replace the occupant detection ECU with a new one.

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      Tip:

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

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

    4. Clear the DTCs stored in the occupant detection ECU.

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      1. Body Electrical > Occupant Detection > Clear DTCs


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

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      1. Body Electrical > SRS Airbag > Clear DTCs


    6. Turn the power switch off.

    7. Turn the power switch on (IG), and wait for at least 10 seconds.

    8. Check for DTCs.

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      1. Body Electrical > Occupant Detection > Trouble Codes


      OK
      DTC B1780 is not output.
      Tip:

      Codes other than DTC B1780 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. Restore the occupant detection ECU that was installed for testing to its original location.

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      Result
      Proceed to
      OK
      NG

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  5. Click here

    REPLACE OCCUPANT DETECTION ECU


    1. Turn the power switch off.

    2. Disconnect the cable from the negative (-) auxiliary battery terminal.

    3. Replace the occupant detection ECU with a new one.

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

      Result
      Proceed to
      NEXT

  6. Click here

    PERFORM ZERO POINT CALIBRATION


    1. Using the GTS, perform Zero Point Calibration.

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      1. Body Electrical > Occupant Detection > Utility
        Tester Display
        Zero Point Calibration




      Result
      Proceed to
      NEXT

    • NEXT

      END (OCCUPANT DETECTION ECU WAS DEFECTIVE)

  7. Click here

    REPLACE FRONT SEAT ADJUSTER ASSEMBLY RH


    1. Turn the power switch off.

    2. Disconnect the cable from the negative (-) auxiliary battery terminal.

    3. Replace the front seat adjuster assembly RH with a new one.

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

      Result
      Proceed to
      NEXT

  8. Click here

    PERFORM ZERO POINT CALIBRATION


    1. Using the GTS, perform Zero Point Calibration.

      Click here


      1. Body Electrical > Occupant Detection > Utility
        Tester Display
        Zero Point Calibration




      Result
      Proceed to
      NEXT

    • NEXT

      END (FRONT SEAT ADJUSTER ASSEMBLY RH WAS DEFECTIVE)