Toyota CH-R Service Manual: Rear Occupant Classification Sensor LH Circuit Malfunction (B1782)

Toyota CH-R Service Manual / Supplemental Restraint Systems / Occupant Classification System / Rear Occupant Classification Sensor LH Circuit Malfunction (B1782)

DESCRIPTION

The rear occupant classification sensor LH circuit consists of the occupant detection ECU and rear in weight detection sensor sub-assembly.

DTC B1782 is stored when a malfunction is detected in the rear in weight detection sensor sub-assembly circuit.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B1782	Rear Occupant Classification Sensor LH Circuit Malfunction	Any of the following conditions is met: The occupant detection ECU detects a line short in the rear in weight detection sensor sub-assembly circuit. The occupant detection ECU detects a line short to ground in the rear in weight detection sensor sub-assembly circuit. The occupant detection ECU detects a line short to B+ in the rear in weight detection sensor sub-assembly circuit. The occupant detection ECU detects a line open in the rear in weight detection sensor sub-assembly circuit. Rear in weight detection sensor sub-assembly malfunction Occupant detection ECU malfunction	Front seat wire RH Rear in weight detection sensor sub-assembly (Front seat adjuster assembly RH)* Occupant detection ECU

*: The rear in weight detection sensor sub-assembly is built into the front seat adjuster assembly RH.

DTC Detection Conditions

		Vehicle Condition
		Pattern 1	Pattern 2	Pattern 3	Pattern 4	Pattern 5	Pattern 6
Diagnosis Condition	Ignition switch ON	○	○	○	○	○	○
Malfunction Status	The occupant detection ECU detects a line short in the rear in weight detection sensor sub-assembly circuit.	○	-	-	-	-	-
	The occupant detection ECU detects a line short to ground in the rear in weight detection sensor sub-assembly circuit.	-	○	-	-	-	-
	The occupant detection ECU detects a line short to B+ in the rear in weight detection sensor sub-assembly circuit.	-	-	○	-	-	-
	The occupant detection ECU detects a line open in the rear in weight detection sensor sub-assembly circuit.	-	-	-	○	-	-
	Rear in weight detection sensor sub-assembly malfunction	-	-	-	-	○	-
	Occupant detection ECU malfunction	-	-	-	-	-	○
Detection Time		-	-	-	-	-	-
Number of Trips		1 trip	1 trip	1 trip	1 trip	1 trip	1 trip

HINT:

DTC will be output when conditions for either of the patterns in the table above are met.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

HINT:

When DTC B1650/32 is stored as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant detection ECU. When DTC B1782 is output, perform troubleshooting for this DTC first.
If it is difficult to perform troubleshooting (wire harness inspection), remove the front passenger seat installation bolts to see under the seat cushion.
In the above case, lift and hold the seat so that it does not fall down. Hold the seat only as necessary because holding the seat for a long period of time may cause seat rail deformation.

PROCEDURE

1.	CHECK CONNECTORS

(a) Turn the ignition switch off.

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

(c) Check that the connectors are properly connected to the occupant detection ECU and rear in weight detection sensor sub-assembly.

OK:

The connectors are properly connected.

HINT:

If the connectors are not properly connected, reconnect the connectors and proceed to the next inspection.

(d) Disconnect the connectors from the occupant detection ECU and rear in weight detection sensor sub-assembly.

(e) Check that the terminals of the connectors are not deformed or damaged.

OK:

The terminals are not deformed or damaged.

REPLACE FRONT SEAT WIRE RH

2.	CHECK FRONT SEAT WIRE RH (SHORT TO B+)

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

*1	Rear In Weight Detection Sensor Sub-assembly
*2	Occupant Detection ECU
*3	Front Seat Wire RH
*a	Front view of wire harness connector (to Occupant Detection ECU)

(b) Turn the ignition switch to ON.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
Y5-2 (SVC3) - Body ground	Ignition switch ON	Below 1 V
Y5-4 (SIG3) - Body ground	Ignition switch ON	Below 1 V
Y5-6 (SGD3) - Body ground	Ignition switch ON	Below 1 V

(d) Turn the ignition switch off.

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

GO TO STEP 12

3.	CHECK FRONT SEAT WIRE RH (OPEN)

(a) Using service wires, connect terminals 1 (SVC) and 3 (SGD), and terminals 2 (SIG) and 3 (SGD) of connector C.

NOTICE:

Do not forcibly insert the service wire into the terminals of the connector when connecting the wire.

*1	Rear In Weight Detection Sensor Sub-assembly
*2	Occupant Detection ECU
*3	Front Seat Wire RH
*4	Service Wire
*a	Front view of wire harness connector (to Occupant Detection ECU)
*b	Front view of wire harness connector (to Rear In Weight Detection Sensor Sub-assembly)

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
Y5-2 (SVC3) - Y5-6 (SGD3)	Always	Below 1 Ω
Y5-4 (SIG3) - Y5-6 (SGD3)	Always	Below 1 Ω

REPLACE FRONT SEAT WIRE RH

4.	CHECK FRONT SEAT WIRE RH (SHORT)

(a) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
Y5-2 (SVC3) - Y5-6 (SGD3)	Always	1 MΩ or higher
Y5-4 (SIG3) - Y5-6 (SGD3)	Always	1 MΩ or higher
Y5-2 (SVC3) - Y5-4 (SIG3)	Always	1 MΩ or higher

*1	Rear In Weight Detection Sensor Sub-assembly
*2	Occupant Detection ECU
*3	Front Seat Wire RH
*a	Front view of wire harness connector (to Occupant Detection ECU)

REPLACE FRONT SEAT WIRE RH

5.	CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)

(a) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
Y5-2 (SVC3) - Body ground	Always	1 MΩ or higher
Y5-4 (SIG3) - Body ground	Always	1 MΩ or higher
Y5-6 (SGD3) - Body ground	Always	1 MΩ or higher

*1	Rear In Weight Detection Sensor Sub-assembly
*2	Occupant Detection ECU
*3	Front Seat Wire RH
*a	Front view of wire harness connector (to Occupant Detection ECU)

REPLACE FRONT SEAT WIRE RH

CHECK DTC

(a) Connect the connectors to the occupant detection ECU and rear in weight detection sensor sub-assembly.

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

Click here

Body Electrical > Occupant Detection > Clear DTCs

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

Click here

Body Electrical > SRS Airbag > Clear DTCs

(e) Turn the ignition switch off.

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

(g) Check for DTCs.

Click here

Body Electrical > Occupant Detection > Trouble Codes

OK:

DTC B1782 is not output.

HINT:

Codes other than DTC B1782 may be output at this time, but they are not related to this check.

(h) Turn the ignition switch off.

USE SIMULATION METHOD TO CHECK

7.	CHECK OCCUPANT DETECTION ECU

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

(b) Replace the occupant detection ECU with a known good one.

Click here

HINT:

Perform the following inspection using known good parts from another vehicle if possible.

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

Click here

Body Electrical > Occupant Detection > Clear DTCs

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

Click here

Body Electrical > SRS Airbag > Clear DTCs

(f) Turn the ignition switch off.

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

(h) Check for DTCs.

Click here

Body Electrical > Occupant Detection > Trouble Codes

OK:

DTC B1782 is not output.

HINT:

Codes other than DTC B1782 may be output at this time, but they are not related to this check.

(i) Turn the ignition switch off.

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

(k) Restore the occupant detection ECU that was installed for testing to its original location.

Click here

GO TO STEP 10

8.	REPLACE OCCUPANT DETECTION ECU

(a) Turn the ignition switch off.

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

Click here

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

9.	PERFORM ZERO POINT CALIBRATION

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

Click here

Body Electrical > Occupant Detection > Utility

Tester Display
Zero Point Calibration

END

10.	REPLACE FRONT SEAT ADJUSTER ASSEMBLY RH

(a) Turn the ignition switch off.

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

Click here

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

11.	PERFORM ZERO POINT CALIBRATION

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

Click here

Body Electrical > Occupant Detection > Utility

Tester Display
Zero Point Calibration

END

12.	REPLACE FRONT SEAT ADJUSTER ASSEMBLY RH

(a) Replace the front seat adjuster assembly RH.

Click here

NOTICE:

Replace the front seat wire RH at the same time.

HINT:

When the front seat wire RH has a short to B+, the rear in weight detection sensor sub-assembly will be damaged. Therefore, replace the front seat wire RH and the front seat adjuster assembly RH, which includes the rear in weight detection sensor sub-assembly.

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

13.	PERFORM ZERO POINT CALIBRATION

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

Click here

Body Electrical > Occupant Detection > Utility

Tester Display
Zero Point Calibration

END

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