OCCUPANT CLASSIFICATION SYSTEM, Diagnostic DTC:B1780

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

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

    One of the following conditions is met:

  • Occupant detection ECU detects a line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to +B signal in the front occupant classification sensor LH circuit for 2 seconds.

  • Front occupant classification sensor LH malfunction.

  • Occupant detection ECU malfunction.

  • Separate type front seat cushion spring assembly (front occupant classification sensor LH)*1

  • Front seat adjuster assembly RH (front occupant classification sensor LH)*2

  • Front seat wire LH*1

  • Front seat wire RH*2

  • Occupant detection ECU

Tech Tips


  • When DTC B1650/32 is stored as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1780 of the occupant classification system.

  • Use the GTS to check for DTCs of the occupant detection ECU, otherwise the DTCs cannot be read.

WIRING DIAGRAM

B0024ATE81
for RHD
*a SVC
*b SGD
*c Separate Type Front Seat Cushion Spring Assembly (Front Occupant Classification Sensor LH)
*d Occupant Detection ECU
B0024ATE82
for LHD
*a SVC
*b SGD
*c Front Seat Adjuster Assembly RH (Front Occupant Classification Sensor LH)
*d Occupant Detection ECU

CAUTION / NOTICE / HINT

Note

When disconnecting the cable, some systems need to be initialized after the cable is reconnected

Click here

Tech Tips


  • If troubleshooting (wire harness inspection) is difficult to perform, remove the front seat LH*1 and RH*2 installation bolts to see the undersurface of the seat cushion.

  • In the above case, hold the seat so that it does not fall down. Holding the seat for a long period of time may cause problems, such as seat rail deformation. Hold the seat up only for as long as necessary.


    • *1: for RHD

    • *2: for LHD

PROCEDURE


  1. CHECK DTC


    1. Turn the ignition switch to ON, and wait for at least 60 seconds.

    2. Clear the DTCs.

      Click here


      Body Electrical > Occupant Detection > Clear DTCs

      Tech Tips


      • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag sensor assembly.

      • Use the GTS to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.

    3. Turn the ignition switch off.

    4. Turn the ignition switch to ON, and wait for at least 60 seconds.

    5. Check for DTCs.

      Click here


      Body Electrical > Occupant Detection > Trouble Codes
      Result
      Proceed to
      DTC B1780 is not output
      DTC B1780 is output

      Tech Tips

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


    DTC B1780 is not output

    USE SIMULATION METHOD TO CHECK Click here

    DTC B1780 is output

  2. 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

    Connectors are not properly connected

    CONNECT CONNECTORS

    Connectors are properly connected

  3. CHECK CONNECTOR


    1. B0026D6C02
      *A for RHD
      *B for LHD
      *1 Front Occupant Classification Sensor LH
      *2 Occupant Detection ECU
      *3 Front Seat Wire LH
      *4 Front Seat Wire RH

      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.

      Click here

      Result
      Proceed to
      Connectors are not deformed or damaged (for RHD)
      Connectors are not deformed or damaged (for LHD)
      Connectors are deformed or damaged (for RHD)
      Connectors are deformed or damaged (for LHD)

    Connectors are not deformed or damaged (for LHD)

    CHECK FRONT SEAT WIRE RH Click here

    Connectors are deformed or damaged (for RHD)

    REPLACE FRONT SEAT WIRE LH

    Connectors are deformed or damaged (for LHD)

    REPLACE FRONT SEAT WIRE RH

    Connectors are not deformed or damaged (for RHD)

  4. CHECK FRONT SEAT WIRE LH


    1. B0025CPC01
      *1 Front Seat Wire LH
      *2 Front Occupant Classification Sensor LH
      *3 Occupant Detection ECU
      *4 Service Wire
      *5 Connector C
      *6 Connector B
      *a

      Front view of wire harness connector

      (to Front Occupant Classification Sensor LH)
      *b

      Front view of wire harness connector

      (to Occupant Detection ECU)

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

    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
      T9-11 (SVC1) - Body ground Ignition switch ON Below 1 V
      T9-7 (SIG1) - Body ground
      T9-1 (SGD1) - 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 wires into the terminals of the connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      T9-11 (SVC1) - T9-1 (SGD1) Always Below 1 Ω
      T9-7 (SIG1) - T9-1 (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
      T9-11 (SVC1) - T9-1 (SGD1) Always 1 MΩ or higher
      T9-7 (SIG1) - T9-1 (SGD1)
      T9-11 (SVC1) - T9-7 (SIG1)
      T9-11 (SVC1) - Body ground
      T9-7 (SIG1) - Body ground
      T9-1 (SGD1) - Body ground
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE FRONT SEAT WIRE LH

    OK

  5. 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.

      Click here


      Body Electrical > Occupant Detection > Clear DTCs

      Tech Tips


      • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag sensor assembly.

      • Use the GTS to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.

    5. Turn the ignition switch off.

    6. Turn the ignition switch to ON, and wait for at least 60 seconds.

    7. Check for DTCs.

      Click here


      Body Electrical > Occupant Detection > Trouble Codes
      Result
      Proceed to
      DTC B1780 is not output
      DTC B1780 is output

      Tech Tips

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


    DTC B1780 is not output

    USE SIMULATION METHOD TO CHECK Click here

    DTC B1780 is output

  6. REPLACE 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.

      Click here

      Result
      Proceed to
      "Zero Point Calibration is complete." is displayed

      Tech Tips

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


    "Zero Point Calibration is complete." is displayed

  7. PERFORM ZERO POINT CALIBRATION


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

    2. Turn the ignition switch to ON.

    3. Perform the zero point calibration.

      Click here

      Result
      Proceed to
      "Zero Point Calibration is complete." is displayed
      "Zero Point Calibration is complete." is not displayed

    "Zero Point Calibration is complete." is not displayed

    REPLACE SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY (FRONT OCCUPANT CLASSIFICATION SENSOR LH) Click here

    "Zero Point Calibration is complete." is displayed

  8. PERFORM SENSITIVITY CHECK


    1. Perform the sensitivity check.

      Click here

      Standard
      27 to 33 kg (59.5 to 72.8 lb)
      Result
      Proceed to
      OK
      NG

    NG

    GO TO STEP 10 Click here

    OK

  9. CHECK DTC


    1. Clear the DTCs.

      Click here


      Body Electrical > Occupant Detection > Clear DTCs

      Tech Tips


      • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag sensor assembly.

      • Use the GTS to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.

    2. Turn the ignition switch off.

    3. Turn the ignition switch to ON, and wait for at least 60 seconds.

    4. Check for DTCs.

      Click here


      Body Electrical > Occupant Detection > Trouble Codes
      Result
      Proceed to
      DTC B1780 is not output
      DTC B1780 is output

      Tech Tips

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


    DTC B1780 is not output

    END (OCCUPANT DETECTION ECU WAS DEFECTIVE)

    DTC B1780 is output

  10. REPLACE SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY (FRONT OCCUPANT CLASSIFICATION SENSOR LH)


    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 separate type front seat cushion spring assembly.

      for Manual Seat: Click here

      for Power Seat: Click here

      Tech Tips

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

      Result
      Proceed to
      NEXT

    NEXT

  11. PERFORM ZERO POINT CALIBRATION


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

    2. Turn the ignition switch to ON.

    3. Perform the zero point calibration.

      Click here

      Result
      Proceed to
      "Zero Point Calibration is complete." is displayed

    "Zero Point Calibration is complete." is displayed

  12. PERFORM SENSITIVITY CHECK


    1. Perform the sensitivity check.

      Click here

      Standard
      27 to 33 kg (59.5 to 72.8 lb)
      Result
      Proceed to
      NEXT

    NEXT

    END (SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY [FRONT OCCUPANT CLASSIFICATION SENSOR LH] WAS DEFECTIVE)

  13. CHECK FRONT SEAT WIRE RH


    1. B0025CPC02
      *1 Front Seat Wire RH
      *2 Front Occupant Classification Sensor LH
      *3 Occupant Detection ECU
      *4 Service Wire
      *5 Connector C
      *6 Connector B
      *a

      Front view of wire harness connector

      (to Front Occupant Classification Sensor LH)
      *b

      Front view of wire harness connector

      (to Occupant Detection ECU)

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

    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
      S9-11 (SVC1) - Body ground Ignition switch ON Below 1 V
      S9-7 (SIG1) - Body ground
      S9-1 (SGD1) - 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 wires into the terminals of the connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      S9-11 (SVC1) - S9-1 (SGD1) Always Below 1 Ω
      S9-7 (SIG1) - S9-1 (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
      S9-11 (SVC1) - S9-1 (SGD1) Always 1 MΩ or higher
      S9-7 (SIG1) - S9-1 (SGD1)
      S9-11 (SVC1) - S9-7 (SIG1)
      S9-11 (SVC1) - Body ground
      S9-7 (SIG1) - Body ground
      S9-1 (SGD1) - Body ground
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE FRONT SEAT WIRE RH

    OK

  14. 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.

      Click here


      Body Electrical > Occupant Detection > Clear DTCs

      Tech Tips


      • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag sensor assembly.

      • Use the GTS to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.

    5. Turn the ignition switch off.

    6. Turn the ignition switch to ON, and wait for at least 60 seconds.

    7. Check for DTCs.

      Click here


      Body Electrical > Occupant Detection > Trouble Codes
      Result
      Proceed to
      DTC B1780 is not output
      DTC B1780 is output

      Tech Tips

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


    DTC B1780 is not output

    USE SIMULATION METHOD TO CHECK Click here

    DTC B1780 is output

  15. REPLACE 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.

      Click here

      Result
      Proceed to
      "Zero Point Calibration is complete." is displayed

      Tech Tips

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


    "Zero Point Calibration is complete." is displayed

  16. PERFORM ZERO POINT CALIBRATION


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

    2. Turn the ignition switch to ON.

    3. Perform the zero point calibration.

      Click here

      Result
      Proceed to
      "Zero Point Calibration is complete." is displayed
      "Zero Point Calibration is complete." is not displayed

    "Zero Point Calibration is complete." is not displayed

    REPLACE FRONT SEAT ADJUSTER ASSEMBLY RH (FRONT OCCUPANT CLASSIFICATION SENSOR LH) Click here

    "Zero Point Calibration is complete." is displayed

  17. PERFORM SENSITIVITY CHECK


    1. Perform the sensitivity check.

      Click here

      Standard
      27 to 33 kg (59.5 to 72.8 lb)
      Result
      Proceed to
      OK
      NG

    NG

    GO TO STEP 19 Click here

    OK

  18. CHECK DTC


    1. Clear the DTCs.

      Click here


      Body Electrical > Occupant Detection > Clear DTCs

      Tech Tips


      • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag sensor assembly.

      • Use the GTS to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.

    2. Turn the ignition switch off.

    3. Turn the ignition switch to ON, and wait for at least 60 seconds.

    4. Check for DTCs.

      Click here


      Body Electrical > Occupant Detection > Trouble Codes
      Result
      Proceed to
      DTC B1780 is not output
      DTC B1780 is output

      Tech Tips

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


    DTC B1780 is not output

    END (OCCUPANT DETECTION ECU WAS DEFECTIVE)

    DTC B1780 is output

  19. REPLACE FRONT SEAT ADJUSTER ASSEMBLY RH (FRONT OCCUPANT CLASSIFICATION SENSOR LH)


    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 front seat adjuster assembly RH.

      for Manual Seat: Click here

      for Power Seat: Click here

      Tech Tips

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

      Result
      Proceed to
      NEXT

    NEXT

  20. PERFORM ZERO POINT CALIBRATION


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

    2. Turn the ignition switch to ON.

    3. Perform the zero point calibration.

      Click here

      Result
      Proceed to
      "Zero Point Calibration is complete." is displayed

    "Zero Point Calibration is complete." is displayed

  21. PERFORM SENSITIVITY CHECK


    1. Perform the sensitivity check.

      Click here

      Standard
      27 to 33 kg (59.5 to 72.8 lb)
      Result
      Proceed to
      NEXT

    NEXT

    END (FRONT SEAT ADJUSTER ASSEMBLY RH [FRONT OCCUPANT CLASSIFICATION SENSOR LH] WAS DEFECTIVE)