DTC    B1780    Front Occupant Classification Sensor LH Circuit Malfunction


DESCRIPTION

The front occupant classification sensor LH circuit consists of the occupant classification ECU and the front occupant classification sensor LH.
DTC B1780 is recorded when a malfunction is detected in the front occupant classification sensor LH circuit.

DTC No.
DTC Detecting Condition
Trouble Area
B1780
  1. Occupant classification ECU detects line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in front occupant classification sensor LH circuit for 2 seconds
  2. Front occupant classification sensor LH malfunction
  3. Occupant classification ECU malfunction
  1. Front seat wire RH
  2. Front seat assembly RH (Front occupant classification sensor LH)
  3. Occupant classification ECU

WIRING DIAGRAM


H100921E20


INSPECTION PROCEDURE

HINT:
  1. If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger seat installation bolts to see the under surface of the seat cushion.
  2. In the above case, hold the seat so that it does not tip over. Holding the seat for a long period of time may cause a problem, such as seat rail deformation. Hold the seat up only for as long as necessary.
1.CHECK DTC
  1. Turn the ignition switch to the on position.

  1. Clear the DTCs stored in the memory (Click here).

    HINT:
    First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
  1. Turn the ignition switch to the lock position.

  1. Turn the ignition switch to the on position.

  1. Check the DTCs (Click here).

    OK:
    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.


OK
USE SIMULATION METHOD TO CHECK
NG


2.CHECK CONNECTION OF CONNECTORS
  1. Turn the ignition switch to the lock position.

  1. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.

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

    OK:
    The connectors are properly connected.


NG
CONNECT CONNECTORS
OK


3.CHECK FRONT SEAT WIRE RH (TO B+)


    C111705E10
  1. Disconnect the connectors from the occupant classification ECU and the front occupant classification sensor LH.

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

  1. Turn the ignition switch to the on position.

  1. Measure the voltage.

    Standard voltage:
    Tester connection
    Condition
    Specified condition
    U1-1 (SGD1) -
    Body ground
    Ignition switch on
    Below 1 V
    U1-7 (SIG1) -
    Body ground
    Ignition switch on
    Below 1 V
    U1-11 (SVC1) -
    Body ground
    Ignition switch on
    Below 1 V


NG
REPAIR OR REPLACE FRONT SEAT WIRE RH
OK


4.CHECK FRONT SEAT WIRE RH (FOR OPEN)


    H100920E01
  1. Turn the ignition switch to the lock position.

  1. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.

  1. Using a service wire, connect U2-1 (SVC1) and U2-3 (SGD1), and connect U2-2 (SIG1) and U2-3 (SGD1) of connector C.

    NOTICE:
    Do not forcibly insert the service wire into the terminals of the connector when connecting.
  1. Measure the resistance.

    Standard resistance:
    Tester connection
    Condition
    Specified condition
    U1-7 (SIG1) -
    U1-1 (SGD1)
    Always
    Below 1 Ω
    U1-11 (SVC1) -
    U1-1 (SGD1)
    Always
    Below 1 Ω


NG
REPAIR OR REPLACE FRONT SEAT WIRE RH
OK


5.CHECK FRONT SEAT WIRE RH (FOR SHORT)


    C111705E10
  1. Disconnect the service wire from connector C.

  1. Measure the resistance.

    Standard resistance:
    Tester connection
    Condition
    Specified condition
    U1-7 (SIG1) -
    U1-1 (SGD1)
    Always
    1 MΩ or higher
    U1-11 (SVC1) -
    U1-1 (SGD1)
    Always
    1 MΩ or higher
    U1-7 (SIG1) -
    U1-11 (SVC1)
    Always
    1 MΩ or higher


NG
REPAIR OR REPLACE FRONT SEAT WIRE RH
OK


6.CHECK FRONT SEAT WIRE RH (TO GROUND)


    C111705E10
  1. Measure the resistance.

    Standard resistance:
    Tester connection
    Condition
    Specified condition
    U1-1 (SGD1) -
    Body ground
    Always
    1 MΩ or higher
    U1-7 (SIG1) -
    Body ground
    Always
    1 MΩ or higher
    U1-11 (SVC1) -
    Body ground
    Always
    1 MΩ or higher


NG
REPAIR OR REPLACE FRONT SEAT WIRE RH
OK


7.CHECK DTC
  1. Connect the connectors to the occupant classification ECU and the front occupant classification sensor LH.

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

  1. Turn the ignition switch to the on position.

  1. Clear the DTCs stored in the memory (Click here).

    HINT:
    First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
  1. Turn the ignition switch to the lock position.

  1. Turn the ignition switch to the on position.

  1. Check the DTCs (Click here).

    OK:
    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.


OK
USE SIMULATION METHOD TO CHECK
NG


8.REPLACE OCCUPANT CLASSIFICATION ECU
  1. Turn the ignition switch to the lock position.

  1. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.

  1. Replace the occupant classification ECU (Click here).

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

NEXT


9.PERFORM ZERO POINT CALIBRATION
  1. Connect the negative (-) terminal cable to the battery.

  1. Connect the Techstream to the DLC3.

  1. Turn the ignition switch to the on position.

  1. Using the Techstream, perform the zero point calibration (Click here).

    OK:
    COMPLETED is displayed.


NG
Go to step 12
OK


10.PERFORM SENSITIVITY CHECK
  1. Using the Techstream, perform the sensitivity check (Click here).

    1. Confirm that nothing is placed on the passenger seat.

    2. Confirm that the beginning sensor reading is within the standard range.

      Standard range:
      -3.2 to 3.2 kg (-7 to 7 lb)
    3. Place a 30 kg (66.14 lb) weight (e.g. a lead mass) onto the front passenger seat.

    4. Confirm that the sensitivity is within the standard range.

      Standard range:
      27 to 33 kg (59.52 to 72.75 lb)

      HINT:
      When performing the sensitivity check, use a solid metal weight (the check result may not be accurate if a liquid weight is used).


NG
Go to step 12
OK


11.CHECK DTC
  1. Connect the negative (-) terminal cable to the battery.

  1. Turn the ignition switch to the on position.

  1. Clear the DTCs stored in the memory (Click here).

    HINT:
    First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
  1. Turn the ignition switch to the lock position.

  1. Turn the ignition switch to the on position.

  1. Check the DTCs (Click here).

    OK:
    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.


OK
END
NG


12.REPLACE FRONT SEAT ASSEMBLY RH
  1. Turn the ignition switch to the lock position.

  1. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.

  1. Replace the front seat assembly RH (Click here ).


NEXT


13.PERFORM ZERO POINT CALIBRATION
  1. Connect the negative (-) terminal cable to the battery.

  1. Connect the Techstream to the DLC3.

  1. Turn the ignition switch to the on position.

  1. Using the Techstream, perform the zero point calibration (Click here).

    OK:
    COMPLETED is displayed.

NEXT


14.PERFORM SENSITIVITY CHECK
  1. Using the Techstream, perform the sensitivity check (Click here).

    1. Confirm that nothing is placed on the passenger seat.

    2. Confirm that the beginning sensor reading is within the standard range.

      Standard range:
      -3.2 to 3.2 kg (-7 to 7 lb)
    3. Place a 30 kg (66.14 lb) weight (e.g. a lead mass) onto the front passenger seat.

    4. Confirm that the sensitivity is within the standard range.

      Standard range:
      27 to 33 kg (59.52 to 72.75 lb)

      HINT:
      When performing the sensitivity check, use a solid metal weight (the check result may not be accurate if a liquid weight is used).

NEXT

END