Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Front Occupant Classification Sensor LH Collision Detection (B1785)

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.

• *: 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 separate type front seat cushion spring 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

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

Click here

OK:

"Zero Point Calibration is complete." is displayed.

NG

GO TO STEP 5

OK

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

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

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

(d) Turn the power switch off.

(e) Turn the power switch on (IG), and wait for at least 10 seconds.

(f) Check for DTCs.

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.

OK

END

NG

(a) Turn the power switch off.

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

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

Click here

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

NEXT

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

Click here

NEXT

END

(a) Turn the power switch off.

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

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

Click here

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

NEXT

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

Click here

NEXT

END