Toyota 4Runner: Rear Occupant Classification Sensor LH Collision Detection (B1787)

Toyota 4Runner Service Manual / Vehicle Interior / Supplemental Restraint Systems / Occupant Classification System / Rear Occupant Classification Sensor LH Collision Detection (B1787)

DESCRIPTION

DTC B1787 is stored when the occupant classification ECU receives a collision detection signal, which is sent by the rear occupant classification sensor LH when an accident occurs.

DTC B1787 is also stored when the separate type front seat cushion spring RH is subjected to a strong impact, even if an actual accident has not occurred.

However, when the occupant classification ECU outputs a collision detection signal, even if the vehicle has not been in a collision, DTC B1787 can be cleared by conducting the zero point calibration and sensitivity check.

Therefore, if DTC B1787 is output, first perform the zero point calibration and sensitivity check.

DTC Code	DTC Detection Condition	Trouble Area
B1787	Either condition is met: Occupant classification ECU receives a collision detection signal, which is sent by the rear occupant classification sensor LH when an accident occurs. Separate type front seat cushion spring RH is subjected to a strong impact, regardless of whether or not an actual accident has occurred.	Separate type front seat cushion spring RH (Rear occupant classification sensor LH) Occupant classification ECU

HINT:

When DTC B1650/32 is stored as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1787 of the occupant classification system.
Use the Techstream to check for DTCs of the occupant classification ECU, otherwise the DTCs cannot be read.

WIRING DIAGRAM

PROCEDURE

1.	CHECK FOR DTC

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

(b) Clear the DTCs stored in the center airbag sensor (See page ).

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

(e) Using the Techstream, check for DTCs of the occupant classification ECU (See page ).

OK:

DTC B1787 is not output.

HINT:

DTCs other than DTC B1787 may be output at this time, but they are not related to this check.

USE SIMULATION METHOD TO CHECK

2.	PERFORM ZERO POINT CALIBRATION

(a) Using the Techstream, perform the zero point calibration (See page ).

OK:

"Zero Point Calibration is complete." is displayed.

GO TO STEP 5

3.	PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform the sensitivity check (See page ).

Standard range:

27 to 33 kg (59.5 to 72.8 lb)

GO TO STEP 5

4.	CHECK FOR DTC

(a) Clear the DTCs stored in the center airbag sensor (See page ).

(b) Turn the ignition switch off.

(d) Using the Techstream, check for DTCs of the occupant classification ECU (See page ).

OK:

DTC B1787 is not output.

HINT:

DTCs other than DTC B1787 may be output at this time, but they are not related to this check.

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, and wait for at least 90 seconds.

(1) Replace the separate type front seat cushion spring RH (See page ).

(d) for Power Seat:

(1) Replace the separate type front seat cushion spring RH (See page ).

HINT:

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

6.	PERFORM ZERO POINT CALIBRATION

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

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

OK:

"Zero Point Calibration is complete." is displayed.

GO TO STEP 9

7.	PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform the sensitivity check (See page ).

Standard range:

27 to 33 kg (59.5 to 72.8 lb)

GO TO STEP 9

8.	CHECK FOR DTC

(a) Clear the DTCs stored in memory (See page ).

HINT:

First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.
Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.

(b) Turn the ignition switch off.

(d) Using the Techstream, check for DTCs of the occupant classification ECU (See page ).

OK:

DTC B1787 is not output.

HINT:

DTCs other than DTC B1787 may be output at this time, but they are not related to this check.

END

9.	REPLACE OCCUPANT CLASSIFICATION ECU

(a) Turn the ignition switch off.

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

HINT:

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

10.	PERFORM ZERO POINT CALIBRATION

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

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

OK:

"Zero Point Calibration is complete." is displayed.

11.	PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform the sensitivity check (See page ).

Standard range:

27 to 33 kg (59.5 to 72.8 lb)

END

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DESCRIPTION The rear occupant classification sensor RH circuit consists of the occupant classification ECU and rear occupant classification sensor RH. DTC B1783 is stored when a malfunction is det ...

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