OCCUPANT CLASSIFICATION SYSTEM, Diagnostic DTC:B1785

DTC Code DTC Name
B1785 Front Occupant Classification Sensor LH Collision Detection

DESCRIPTION

DTC B1785 is stored when the occupant detection ECU receives a collision detection signal, which is sent by the front occupant classification sensor LH when an accident occurs.

DTC B1785 is also stored when the separate type front seat cushion spring assembly*1 and front seat adjuster assembly RH*2 is subjected to a strong impact, even if an actual accident has not occurred.

However, when the occupant detection ECU outputs a collision detection signal, even if the vehicle has not been in a collision, DTC B1785 can be cleared by conducting the zero point calibration and sensitivity check.

Therefore, if DTC B1785 is output, first perform the zero point calibration and sensitivity check.

DTC No. Detection Item DTC Detection Condition Trouble Area
B1785 Front Occupant Classification Sensor LH Collision Detection

    Either condition is met:

  • Occupant detection ECU receives a collision detection signal, which is sent by the front occupant classification sensor LH when an accident occurs.

  • Separate type front seat cushion spring assembly*1 and front seat adjuster assembly RH*2 is subjected to a strong impact, regardless of whether or not an actual accident has occurred.

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

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

  • Occupant detection ECU

Tech Tips


  • When DTC B1650/32 is stored as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1785 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

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 B1785 is not output
      DTC B1785 is output

      Tech Tips

      DTCs other than DTC B1785 may be output at this time, but they are not related to this check.


    DTC B1785 is not output

    USE SIMULATION METHOD TO CHECK Click here

    DTC B1785 is output

  2. PERFORM ZERO POINT CALIBRATION


    1. Perform the zero point calibration.

      Click here

      Result
      Result Proceed to
      "Zero Point Calibration is complete." is displayed A
      "Zero Point Calibration is complete." is not displayed (for RHD) B
      "Zero Point Calibration is complete." is not displayed (for LHD) C

    B

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

    C

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

    A

  3. 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 (for RHD)
      NG (for LHD)

    NG (for RHD)

    GO TO STEP 5 Click here

    NG (for LHD)

    GO TO STEP 12 Click here

    OK

  4. 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 B1785 is not output
      DTC B1785 is output (for RHD)
      DTC B1785 is output (for LHD)

      Tech Tips

      DTCs other than DTC B1785 may be output at this time, but they are not related to this check.


    DTC B1785 is not output

    END

    DTC B1785 is output (for LHD)

    GO TO STEP 12 Click here

    DTC B1785 is output (for RHD)

  5. 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

  6. 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 OCCUPANT DETECTION ECU Click here

    "Zero Point Calibration is complete." is displayed

  7. 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 9 Click here

    OK

  8. 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 B1785 is not output
      DTC B1785 is output

      Tech Tips

      DTCs other than DTC B1785 may be output at this time, but they are not related to this check.


    DTC B1785 is not output

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

    DTC B1785 is output

  9. 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

      Tech Tips

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

      Result
      Proceed to
      NEXT

    NEXT

  10. 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

  11. 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 (OCCUPANT DETECTION ECU WAS DEFECTIVE)

  12. 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

  13. 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 OCCUPANT DETECTION ECU Click here

    "Zero Point Calibration is complete." is displayed

  14. 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 16 Click here

    OK

  15. 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 B1785 is not output
      DTC B1785 is output

      Tech Tips

      DTCs other than DTC B1785 may be output at this time, but they are not related to this check.


    DTC B1785 is not output

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

    DTC B1785 is output

  16. 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

      Tech Tips

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

      Result
      Proceed to
      NEXT

    NEXT

  17. 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

  18. 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 (OCCUPANT DETECTION ECU WAS DEFECTIVE)