Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000001HSM2
Model Year Start: 2020 Model: GR Corolla Prod Date Range: [03/2019 - 09/2022]
Title: SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM (for Gasoline Model): B1785; Front Occupant Classification Sensor LH Collision Detection; 2020 - 2022 MY Corolla Corolla Hatchback GR Corolla [03/2019 - 09/2022]

DTC

B1785

Front Occupant Classification Sensor LH Collision Detection

DESCRIPTION

DTC B1785 is stored when the occupant detection ECU receives a collision detection signal sent by the front occupant classification sensor LH in the case of an accident.

DTC B1785 is also stored when the front seat assembly RH is subjected to a strong impact, even if an actual accident did not occur.

If the vehicle was not in a collision, but the occupant detection ECU receives a collision detection signal and stores DTC B1785, the DTC can be cleared by performing zero point calibration. Therefore, if DTC B1785 is output, first perform zero point calibration.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B1785

Front Occupant Classification Sensor LH Collision Detection
  • Front occupant classification sensor LH sensed large load.
  • Front seat adjuster assembly RH malfunction*1
  • Separate type front seat cushion spring assembly RH malfunction*2
  • Front occupant classification sensor LH (Front seat adjuster assembly RH)*1
  • Front occupant classification sensor LH (Separate type front seat cushion spring assembly RH)*2
  • *1: for TMC Made

    The front occupant classification sensor LH is built into the front seat adjuster assembly RH.

  • *2: for TMMMS Made

    The front occupant classification sensor LH is built into the separate type front seat cushion spring assembly RH.

CAUTION / NOTICE / HINT

NOTICE:

  • When this DTC is stored, repair of the malfunction indicated can only be performed by initializing the occupant detection ECU, or replacing the front seat adjuster assembly RH*1 or separate type front seat cushion spring assembly RH*2. Do not replace the occupant detection ECU to repair the malfunction indicated by this DTC.

    If the occupant detection ECU is replaced, this DTC will not be output but the occupant detection system may not function properly.

    *1: for TMC Made

    *2: for TMMMS Made

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

    Click here 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2019]; INTRODUCTION: REPAIR INSTRUCTION: INITIALIZATION 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [09/2019 - 04/2020]; INTRODUCTION: REPAIR INSTRUCTION: INITIALIZATION 2021 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [04/2020 - 09/2022]; INTRODUCTION: REPAIR INSTRUCTION: INITIALIZATION

HINT:

When DTC B165A is stored as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant detection ECU. When DTC B1785 is output, perform troubleshooting for this DTC first.

PROCEDURE

1.

PERFORM ZERO POINT CALIBRATION

(a) Using the Techstream, perform Zero Point Calibration.

Click here 2020 - 2022 MY Corolla Corolla Hatchback GR Corolla [03/2019 - 09/2022]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM (for Gasoline Model): INITIALIZATION

OK:

"Zero Point Calibration is complete." is displayed.

Result

Proceed to

OK

A

NG (for TMC Made)

B

NG (for TMMMS Made)

C
B

GO TO STEP 3

C

GO TO STEP 5

A

2.

CHECK DTC

(a) Turn the ignition switch to ON, and wait for at least 60 seconds.

(b) Clear the DTCs stored in the occupant detection ECU.

Body Electrical > Occupant Detection > Clear DTCs

(c) Clear the DTCs stored in the airbag sensor assembly.

Body Electrical > SRS Airbag > Clear DTCs

(d) Turn the ignition switch off.

(e) Turn the ignition switch to ON, and wait for at least 10 seconds.

(f) Check for DTCs.

Body Electrical > Occupant Detection > Trouble Codes

OK:

DTC B1785 is not output.

HINT:

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

(g) Turn the ignition switch off.

Result

Proceed to

OK

A

NG (for TMC Made)

B

NG (for TMMMS Made)

C
A

END
C

GO TO STEP 5

B

3.

REPLACE FRONT SEAT ADJUSTER ASSEMBLY RH

(a) Turn the ignition switch off.

(b) Disconnect the cable from the negative (-) battery terminal.

(c) Replace the front seat adjuster assembly RH.

Click here 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; SEAT: FRONT SEAT ASSEMBLY (for Manual Seat): REMOVAL

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

NEXT

4.

PERFORM ZERO POINT CALIBRATION

(a) Using the Techstream, perform Zero Point Calibration.

Click here 2020 - 2022 MY Corolla Corolla Hatchback GR Corolla [03/2019 - 09/2022]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM (for Gasoline Model): INITIALIZATION

NEXT

END

5.

REPLACE SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY RH

(a) Turn the ignition switch off.

(b) Disconnect the cable from the negative (-) battery terminal.

(c) Replace the separate type front seat cushion spring assembly RH.

Click here 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; SEAT: FRONT SEAT ASSEMBLY (for Manual Seat): REMOVAL

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

NEXT

GO TO STEP 4