Lexus NX manuals

Lexus NX: Front Occupant Classification Sensor LH Collision Detection (B1785)

Lexus NX Service Manual / Vehicle Interior / Supplemental Restraint Systems / Occupant Classification System / Front Occupant Classification Sensor LH Collision Detection (B1785)

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 front seat adjuster assembly RH 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.
  • Front seat adjuster assembly RH is subjected to a strong impact, regardless of whether or not an actual accident has occurred.
  • Front seat adjuster assembly RH (front occupant classification sensor LH)
  • Occupant detection ECU

HINT:

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

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

Click here

PROCEDURE

1.

CHECK DTC

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

(b) Clear the DTCs.

Click here

Body Electrical > Occupant Detection > Clear DTCs

HINT:

  • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag ECU assembly.
  • Use the Techstream to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.

(c) Turn the power switch off.

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

(e) Check for DTCs.

Click here

Body Electrical > Occupant Detection > Trouble Codes

HINT:

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

DTC B1785 is output

2.

PERFORM ZERO POINT CALIBRATION

(a) Perform the zero point calibration.

Click here

"Zero Point Calibration is complete." is not displayed

GO TO STEP 5

"Zero Point Calibration is complete." is displayed

3.

PERFORM SENSITIVITY CHECK

(a) Perform the sensitivity check.

Click here

Standard:

27 to 33 kg (59.5 to 72.8 lb)

NG

GO TO STEP 5

OK

4.

CHECK DTC

(a) Clear the DTCs.

Click here

Body Electrical > Occupant Detection > Clear DTCs

HINT:

  • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag ECU assembly.
  • Use the Techstream to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.

(b) Turn the power switch off.

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

(d) Check for DTCs.

Click here

Body Electrical > Occupant Detection > Trouble Codes

HINT:

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

GO TO STEP 5

5.

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

(a) Turn the power switch off.

(b) Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.

(c) Replace the front seat adjuster assembly RH.

Click here

HINT:

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

NEXT

6.

PERFORM ZERO POINT CALIBRATION

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

(b) Turn the power switch on (IG).

(c) Perform the zero point calibration.

Click here

"Zero Point Calibration is complete." is not displayed

GO TO STEP 9

"Zero Point Calibration is complete." is displayed

7.

PERFORM SENSITIVITY CHECK

(a) Perform the sensitivity check.

Click here

Standard:

27 to 33 kg (59.5 to 72.8 lb)

NG

GO TO STEP 9

OK

8.

CHECK DTC

(a) Clear the DTCs.

Click here

Body Electrical > Occupant Detection > Clear DTCs

HINT:

  • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag ECU assembly.
  • Use the Techstream to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.

(b) Turn the power switch off.

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

(d) Check for DTCs.

Click here

Body Electrical > Occupant Detection > Trouble Codes

HINT:

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

GO TO STEP 9

9.

REPLACE OCCUPANT DETECTION ECU

(a) Turn the power switch off.

(b) Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.

(c) Replace the occupant detection ECU.

Click here

HINT:

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

NEXT

10.

PERFORM ZERO POINT CALIBRATION

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

(b) Turn the power switch on (IG).

(c) Perform the zero point calibration.

Click here

"Zero Point Calibration is complete." is displayed

11.

PERFORM SENSITIVITY CHECK

(a) Perform the sensitivity check.

Click here

Standard:

27 to 33 kg (59.5 to 72.8 lb)

NEXT

END (OCCUPANT DETECTION ECU WAS DEFECTIVE)

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