SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM (for HV Model): B1785; Front Occupant Classification Sensor LH Collision Detection; 2020 - 2022 MY Corolla Corolla HV [01/2019

Last Modified: 05-13-2024	6.11:8.1.0	Doc ID: RM100000001G4RI
Model Year Start: 2020	Model: Corolla	Prod Date Range: [01/2019 - 09/2022]
Title: SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM (for HV Model): B1785; Front Occupant Classification Sensor LH Collision Detection; 2020 - 2022 MY Corolla Corolla HV [01/2019 - 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	Front occupant classification sensor LH (Front seat adjuster assembly RH)*

*: The front occupant classification sensor LH is built into the front seat adjuster 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. 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.
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.
Click here

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

OK:

"Zero Point Calibration is complete." is displayed.

GO TO STEP 5

CHECK DTC

(a) Turn the power switch on (IG), and wait for at least 60 seconds.

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

Body Electrical > Occupant Detection > Clear DTCs

Body Electrical > SRS Airbag > Clear DTCs

(d) Turn the power switch off.

(e) Turn the power switch on (IG), 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 power switch off.

END

3.	REPLACE FRONT SEAT ADJUSTER ASSEMBLY RH

(a) Turn the power switch off.

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

Click here

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

4.	PERFORM ZERO POINT CALIBRATION

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

Click here

END

5.	REPLACE FRONT SEAT ADJUSTER ASSEMBLY RH

(a) Turn the power switch off.

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

Click here

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

6.	PERFORM ZERO POINT CALIBRATION

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

Click here

END