Toyota Avalon (XX50): Occupant Classification System(for Gasoline Model)

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Vehicle Interior / Supplemental Restraint Systems / Occupant Classification System(for Gasoline Model)

Passenger Side Buckle Switch Circuit Malfunction (B1771)

DESCRIPTION

The front passenger side buckle switch circuit consists of the occupant detection ECU and front passenger side buckle switch (front seat inner belt assembly RH).

DTC B1771 is stored when a malfunction is detected in the front passenger side buckle switch circuit.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B1771	Passenger Side Buckle Switch Circuit Malfunction	The occupant detection ECU detects a line short, short to ground or B+, or an open in the front passenger side buckle switch circuit. Front passenger side buckle switch malfunction Occupant detection ECU malfunction	Front seat wire RH Front passenger side buckle switch (Front seat inner belt assembly RH) Occupant detection ECU

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

After turning the engine 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 is stored as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant detection ECU. When DTC B1771 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 engine 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 front seat inner belt assembly RH.

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 front seat inner belt assembly RH.

(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

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

*1	Front Seat Inner Belt Assembly RH
*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 Front Seat Inner Belt Assembly RH)

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
R7-7 (BSW) - Body ground	Engine switch on (IG)	Below 1 V
R7-9 (BGND) - Body ground	Engine switch on (IG)	Below 1 V

(d) Turn the engine switch off.

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

(f) Using a service wire, connect terminals 2 (BSW) and 1 (BGND) of connector C.

NOTICE:

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

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
R7-7 (BSW) - R7-9 (BGND)	Always	Below 1 Ω

(h) Disconnect the service wire from connector C.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
R7-7 (BSW) - R7-9 (BGND)	Always	1 MΩ or higher
R7-7 (BSW) - Body ground	Always	1 MΩ or higher
R7-9 (BGND) - Body ground	Always	1 MΩ or higher

REPLACE FRONT SEAT WIRE RH

CHECK DTC

(a) Connect the connectors to the occupant detection ECU and front seat inner belt assembly RH.

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

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

Body Electrical > Occupant Detection > Clear DTCs

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

Body Electrical > SRS Airbag > Clear DTCs

(f) Turn the engine switch off.

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

(h) Check for DTCs.

Body Electrical > Occupant Detection > Trouble Codes

OK:

DTC B1771 is not output.

HINT:

Codes other than DTC B1771 may be output at this time, but they are not related to this check.

(i) Turn the engine switch off.

USE SIMULATION METHOD TO CHECK

4.	CHECK FRONT SEAT INNER BELT ASSEMBLY RH

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

(b) Replace the front seat inner belt assembly RH with a known good one.

Click here

HINT:

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

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

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

Body Electrical > Occupant Detection > Clear DTCs

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

Body Electrical > SRS Airbag > Clear DTCs

(g) Turn the engine switch off.

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

(i) Check for DTCs.

Body Electrical > Occupant Detection > Trouble Codes

OK:

DTC B1771 is not output.

HINT:

Codes other than DTC B1771 may be output at this time, but they are not related to this check.

(j) Turn the engine switch off.

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

(l) Restore the front seat inner belt assembly RH that was installed for testing to its original location.

Click here

REPLACE FRONT SEAT INNER BELT ASSEMBLY RH

5.	REPLACE OCCUPANT DETECTION ECU

(a) Turn the engine switch off.

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

Click here

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

6.	PERFORM ZERO POINT CALIBRATION

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

Click here

END

Front Occupant Classification Sensor LH Circuit Malfunction (B1780)

DESCRIPTION

The front occupant classification sensor LH circuit consists of the occupant detection ECU and front occupant classification sensor LH.

DTC B1780 is stored when a malfunction is detected in the front occupant classification sensor LH circuit.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B1780	Front Occupant Classification Sensor LH Circuit Malfunction	The occupant detection ECU detects a line short, short to ground or B+, or an open in the front occupant classification sensor LH circuit. Front occupant classification sensor LH malfunction Occupant detection ECU malfunction	Front seat wire RH Front occupant classification sensor LH (Separate type front seat cushion spring assembly RH)* Occupant detection ECU

*: The front occupant classification sensor LH is built into the separate type front seat cushion spring assembly RH.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Click here

HINT:

When DTC B1650 is stored as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant detection ECU. When DTC B1780 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 engine 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 front occupant classification sensor LH.

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 front occupant classification sensor LH.

(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

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

*1	Front Occupant Classification Sensor LH
*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 Front Occupant Classification Sensor LH)

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
R8-1 (SVC1) - Body ground	Engine switch on (IG)	Below 1 V
R8-3 (SIG1) - Body ground	Engine switch on (IG)	Below 1 V
R8-5 (SGD1) - Body ground	Engine switch on (IG)	Below 1 V

(d) Turn the engine switch off.

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

(f) Using service wires, connect terminals 1 (SVC1) and 3 (SGD1), and terminals 2 (SIG1) and 3 (SGD1) of connector C.

NOTICE:

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

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
R8-1 (SVC1) - R8-5 (SGD1)	Always	Below 1 Ω
R8-3 (SIG1) - R8-5 (SGD1)	Always	Below 1 Ω

(h) Disconnect the service wires from connector C.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
R8-1 (SVC1) - R8-5 (SGD1)	Always	1 MΩ or higher
R8-3 (SIG1) - R8-5 (SGD1)	Always	1 MΩ or higher
R8-1 (SVC1) - R8-3 (SIG1)	Always	1 MΩ or higher
R8-1 (SVC1) - Body ground	Always	1 MΩ or higher
R8-3 (SIG1) - Body ground	Always	1 MΩ or higher
R8-5 (SGD1) - Body ground	Always	1 MΩ or higher

REPLACE FRONT SEAT WIRE RH

CHECK DTC

(a) Connect the connectors to the occupant detection ECU and front occupant classification sensor LH.

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

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

Body Electrical > Occupant Detection > Clear DTCs

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

Body Electrical > SRS Airbag > Clear DTCs

(f) Turn the engine switch off.

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

(h) Check for DTCs.

Body Electrical > Occupant Detection > Trouble Codes

OK:

DTC B1780 is not output.

HINT:

Codes other than DTC B1780 may be output at this time, but they are not related to this check.

(i) Turn the engine switch off.

USE SIMULATION METHOD TO CHECK

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

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

Body Electrical > Occupant Detection > Clear DTCs

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

Body Electrical > SRS Airbag > Clear DTCs

(g) Turn the engine switch off.

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

(i) Check for DTCs.

Body Electrical > Occupant Detection > Trouble Codes

OK:

DTC B1780 is not output.

HINT:

Codes other than DTC B1780 may be output at this time, but they are not related to this check.

(j) Turn the engine switch off.

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

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

Click here

GO TO STEP 7

5.	REPLACE OCCUPANT DETECTION ECU

(a) Turn the engine switch off.

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

Click here

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

6.	PERFORM ZERO POINT CALIBRATION

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

Click here

END

7.	REPLACE SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY RH

(a) Turn the engine switch off.

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

Click here

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

8.	PERFORM ZERO POINT CALIBRATION

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

Click here

END

Rear Occupant Classification Sensor LH Circuit Malfunction (B1782)

DESCRIPTION

The rear occupant classification sensor LH circuit consists of the occupant detection ECU and rear occupant classification sensor LH.

DTC B1782 is stored when a malfunction is detected in the rear occupant classification sensor LH circuit.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B1782	Rear Occupant Classification Sensor LH Circuit Malfunction	The occupant detection ECU detects a line short, short to ground or B+, or an open in the rear occupant classification sensor LH circuit. Rear occupant classification sensor LH malfunction Occupant detection ECU malfunction	Front seat wire RH Rear occupant classification sensor LH (Separate type front seat cushion spring assembly RH)* Occupant detection ECU

*: The rear occupant classification sensor LH is built into the separate type front seat cushion spring assembly RH.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Click here

HINT:

When DTC B1650 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 engine 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 occupant classification sensor LH.

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 occupant classification sensor LH.

(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

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

*1	Rear Occupant Classification Sensor LH
*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 Occupant Classification Sensor LH)

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
R8-2 (SVC3) - Body ground	Engine switch on (IG)	Below 1 V
R8-4 (SIG3) - Body ground	Engine switch on (IG)	Below 1 V
R8-6 (SGD3) - Body ground	Engine switch on (IG)	Below 1 V

(d) Turn the engine switch off.

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

(f) Using service wires, connect terminals 1 (SVC3) and 3 (SGD3), and terminals 2 (SIG3) and 3 (SGD3) of connector C.

NOTICE:

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

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
R8-2 (SVC3) - R8-6 (SGD3)	Always	Below 1 Ω
R8-4 (SIG3) - R8-6 (SGD3)	Always	Below 1 Ω

(h) Disconnect the service wires from connector C.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
R8-2 (SVC3) - R8-6 (SGD3)	Always	1 MΩ or higher
R8-4 (SIG3) - R8-6 (SGD3)	Always	1 MΩ or higher
R8-2 (SVC3) - R8-4 (SIG3)	Always	1 MΩ or higher
R8-2 (SVC3) - Body ground	Always	1 MΩ or higher
R8-4 (SIG3) - Body ground	Always	1 MΩ or higher
R8-6 (SGD3) - Body ground	Always	1 MΩ or higher

REPLACE FRONT SEAT WIRE RH

CHECK DTC

(a) Connect the connectors to the occupant detection ECU and rear occupant classification sensor LH.

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

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

Body Electrical > Occupant Detection > Clear DTCs

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

Body Electrical > SRS Airbag > Clear DTCs

(f) Turn the engine switch off.

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

(h) Check for DTCs.

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 engine switch off.

USE SIMULATION METHOD TO CHECK

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

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

Body Electrical > Occupant Detection > Clear DTCs

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

Body Electrical > SRS Airbag > Clear DTCs

(g) Turn the engine switch off.

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

(i) Check for DTCs.

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.

(j) Turn the engine switch off.

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

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

Click here

GO TO STEP 7

5.	REPLACE OCCUPANT DETECTION ECU

(a) Turn the engine switch off.

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

Click here

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

6.	PERFORM ZERO POINT CALIBRATION

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

Click here

END

7.	REPLACE SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY RH

(a) Turn the engine switch off.

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

Click here

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

8.	PERFORM ZERO POINT CALIBRATION

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

Click here

END

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.

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. Separate type front seat cushion spring assembly RH malfunction	Front occupant classification sensor LH (Separate type front seat cushion spring assembly RH)*

*: 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 engine 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 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 engine 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 engine switch off.

(e) Turn the engine 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 engine switch off.

END

3.	REPLACE SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY RH

(a) Turn the engine switch off.

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

Click here

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

4.	PERFORM ZERO POINT CALIBRATION

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

Click here

END

5.	REPLACE SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY RH

(a) Turn the engine switch off.

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

Click here

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

6.	PERFORM ZERO POINT CALIBRATION

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

Click here

END

Rear Occupant Classification Sensor LH Collision Detection (B1787)

DESCRIPTION

DTC B1787 is stored when the occupant detection ECU receives a collision detection signal sent by the rear occupant classification sensor LH in the case of an accident.

DTC B1787 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 B1787, the DTC can be cleared by performing zero point calibration. Therefore, if DTC B1787 is output, first perform zero point calibration.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B1787	Rear Occupant Classification Sensor LH Collision Detection	Rear occupant classification sensor LH sensed large load. Separate type front seat cushion spring assembly RH malfunction	Rear occupant classification sensor LH (Separate type front seat cushion spring assembly RH)*

*: The rear 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 engine 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 B165A is stored as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant detection ECU. When DTC B1787 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 engine 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 engine switch off.

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

(f) Check for DTCs.

Body Electrical > Occupant Detection > Trouble Codes

OK:

DTC B1787 is not output.

HINT:

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

(g) Turn the engine switch off.

END

3.	REPLACE SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY RH

(a) Turn the engine switch off.

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

Click here

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

4.	PERFORM ZERO POINT CALIBRATION

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

Click here

END

5.	REPLACE SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY RH

(a) Turn the engine switch off.

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

Click here

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

6.	PERFORM ZERO POINT CALIBRATION

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

Click here

END

Occupant Classification ECU Malfunction (B1795)

DESCRIPTION

DTC B1795 is stored when a malfunction is detected in the occupant detection ECU.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B1795	Occupant Classification ECU Malfunction	Occupant detection ECU malfunction	Occupant detection ECU

CAUTION / NOTICE / HINT

NOTICE:

Click here

HINT:

When DTC B1650 is stored as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant detection ECU. When DTC B1795 is output, perform troubleshooting for this DTC first.

PROCEDURE

CHECK DTC

(a) Turn the engine 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 engine switch off.

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

(f) Check for DTCs.

Body Electrical > Occupant Detection > Trouble Codes

OK:

DTC B1795 is not output.

HINT:

Codes other than DTC B1795 may be output at this time, but they are not related to this check.

(g) Turn the engine switch off.

USE SIMULATION METHOD TO CHECK

2.	REPLACE OCCUPANT DETECTION ECU

(a) Turn the engine switch off.

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

Click here

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

3.	PERFORM ZERO POINT CALIBRATION

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

Click here

END

Yaw Rate Sensor Module Malfunction (B1798,B1799)

DESCRIPTION

The occupant detection ECU receives signals from the acceleration sensor (airbag ECU assembly) and skid control ECU (brake actuator assembly) via CAN communication.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B1798	Yaw Rate Sensor Module Malfunction	Acceleration signals are abnormal	Acceleration sensor (Airbag ECU assembly) CAN communication system Occupant detection ECU
B1799	Vehicle Stability Control ECU Malfunction	Vehicle speed signal from skid control ECU is abnormal	Skid control ECU (Brake actuator assembly) CAN communication system Occupant detection ECU

CAUTION / NOTICE / HINT

NOTICE:

Click here

HINT:

When DTC B1650 is stored as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant detection ECU. When DTC B1798 or B1799 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 DTC (ELECTRONICALLY CONTROLLED BRAKE SYSTEM)

(a) Check for electronically controlled brake system DTCs.

Click here

OK:

DTCs are not output.

GO TO ELECTRONICALLY CONTROLLED BRAKE SYSTEM

2.	CHECK CAN COMMUNICATION SYSTEM

(a) Using the Techstream, check if the CAN communication system is functioning normally.

OK:

CAN communication system is functioning normally.

HINT:

Refer to Communication Bus Check in CAN Communication System.

Click here

GO TO CAN COMMUNICATION SYSTEM

3.	CHECK DTC (HEALTH CHECK)

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(d) Enter the following menus: System Select / Health Check.

OK:

DTCs are not output.

USE SIMULATION METHOD TO CHECK

GO TO OTHER DIAGNOSTIC TROUBLE CODE CHART

Data List / Active Test

DATA LIST / ACTIVE TEST

DATA LIST

HINT:

Using the Techstream to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or signals may be discovered before parts or wiring is disturbed. Reading the Data List information early in troubleshooting is one way to save diagnostic time.

NOTICE:

In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not.

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Occupant Detection / Data List.

(f) Read the Data List according to the display on the Techstream.

Body Electrical > Occupant Detection > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
FL Sensor Weight Information	Front left sensor weight information	Min.: -75.852 kg (-167.223 lb) Max.: 104.737 kg (230.903 lb)	Current value displayed	-
RL Sensor Weight Information	Rear left sensor weight information	Min.: -75.852 kg (-167.223 lb) Max.: 104.737 kg (230.903 lb)	Current value displayed	-
Total Weight Information	Total weight information	Min.: -151.704 kg (-334.446 lb) Max.: 209.475 kg (461.808 lb)	Current value displayed	-
Weight Forward and Rearward Difference	Weight difference between front and rear	Min.: -180.589 kg (-398.126 lb) Max.: 180.589 kg (398.126 lb)	Current value displayed	-
Airbag Total Weight	Total weight information for airbag system	Min.: -161.595 kg (-356.252 lb) Max.: 226.017 kg (498.277 lb)	Current value displayed	-
Belt Warning Total Weight	Total weight information for seat belt warning system	Min.: -155.001 kg (-341.715 lb) Max.: 219.400 kg (483.689 lb)	Current value displayed	-
VSC Status	Vehicle speed status	ON or OFF	ON: Vehicle speed valid	-
VSC Vehicle Speed	Vehicle speed	Min.: 0.00 km/h (0.00 mph) Max.: 327.67 km/h (203.61 mph)	Current value displayed	-
VSC Zero Point1	Zero point for acceleration sensor 1	Min.: -4.5952 m/s2 Max.: 4.5593 m/s2	Current value displayed	-
VSC Zero Point2	Zero point for acceleration sensor 2	Min.: -4.5952 m/s2 Max.: 4.5593 m/s2	Current value displayed	-
VSC Calibration Status	Vehicle stability control calibration status	Calibrated or Uncalibrated	Calibrated	-
VSC Assembly Information	Acceleration sensor information	Reverse Position or Normal Position	Reverse Position or Normal Position	Displays a fixed value for each vehicle.
Yaw Rate/G Sensor Voltage Invalid Flag	Yaw rate and acceleration sensor voltage invalid flag	ON or OFF	ON: Valid	-
Yaw Rate/G Sensor Malfunction Flag1	Malfunction flag for acceleration sensor 1	OK or NG	OK	-
Yaw Rate/G Sensor Invalid Flag1	Invalid flag for acceleration sensor 1	ON or OFF	ON: Valid	-
Yaw Rate/G Sensor Malfunction Flag2	Malfunction flag for acceleration sensor 2	OK or NG	OK	-
Yaw Rate/G Sensor Invalid Flag2	Invalid flag for acceleration sensor 2	ON or OFF	ON: Valid	-
Yaw Rate/G Sensor Assembly Information	Acceleration sensor information for occupant classification system	Unset, Reverse Position or Normal Position	Reverse Position or Normal Position	Displays a fixed value for each vehicle. "Unset" will be displayed for approximately 2 seconds after the engine switch is turned on (IG).
Passenger Detection(Airbag)	Front passenger classification	OFF/Child, CRS1, CRS2, AF05 or AM50	OFF/Child: Vacant or child is seated CRS1: Child restraint system is installed CRS2: Child restraint system is installed AF05: Adult is seated AM50: Adult is seated	-
Passenger Detection(Belt Warning)	Front passenger detection for seat belt warning system	OFF, Baggage or ON	OFF: Seat is vacant Baggage: Seat is occupied by baggage ON: Seat is occupied	-
Driving Status	Driving status	Stop, Drive or Turn	Stop: Vehicle is stopped Drive: Vehicle is being driven straight Turn: Vehicle is turning	-
Passenger Buckle SW	Front passenger side buckle switch	NG, Set or Unset	Set: Front passenger seat belt is fastened Unset: Front passenger seat belt is not fastened	"NG" will be displayed immediately after the engine switch is turned on (IG).
The Number of DTCs	Number of DTC recorded	Min.: 0, Max.: 255	0	The number displayed is the total current DTCs and history DTCs stored (excluding duplicates).

Diagnosis System

DIAGNOSIS SYSTEM

CHECK DLC3

(a) Check the DLC3.

Click here

FUNCTION OF PASSENGER AIRBAG ON/OFF INDICATOR

(a) Initial check

(1) Turn the engine switch on (IG).

(2) The passenger airbag ON/OFF indicator comes on for approximately 4 seconds, then turns off for approximately 2 seconds.

(3) Approximately 6 seconds after the engine switch is turned on (IG), the passenger airbag ON/OFF indicator will indicate ON/OFF depending on the following conditions.

Indicator Operation

Front Passenger Seat Condition	Passenger Airbag ON/OFF Indicator		SRS Warning Light
Front Passenger Seat Condition	ON Indicator	OFF Indicator	SRS Warning Light
Vacant	OFF	ON	OFF
Adult*1 is seated	ON	OFF	OFF
Child*2 is seated	ON or OFF*2	OFF or ON*2	OFF
Child restraint system is installed	OFF	ON	OFF
Occupant classification system failure	OFF	ON	ON

*1: The system judges a person of average adult weight or more as an adult. If a smaller adult sits in the front passenger seat, the system may not recognize them as an adult depending on their physique and posture.
*2: The system may not recognize a child or a child in a child restrain system as a child depending on factors such as the positioning of the child restraint system or the child's physique or posture.

HINT:

The passenger airbag ON/OFF indicator illuminates based on the following timing chart in order to check the indicator light circuit.
When the occupant classification system has a malfunction, both the SRS warning light and passenger airbag ON/OFF indicator ("OFF") come on. In this case, check for airbag system DTCs first.

PASSENGER AIRBAG ON/OFF INDICATOR CHECK

(a) Turn the engine switch on (IG).

(b) Check that the passenger airbag ON/OFF indicator ("ON" and "OFF") comes on for approximately 4 seconds, then turns off for approximately 2 seconds.

HINT:

Refer to the indicator operation table in Function of Passenger Airbag ON/OFF Indicator for the passenger airbag ON/OFF indicator operation when the engine switch is turned on (IG) and approximately 6 seconds elapse.

Diagnostic Trouble Code Chart

DIAGNOSTIC TROUBLE CODE CHART

Occupant Classification System

DTC No.	Detection Item	Link
B1771	Passenger Side Buckle Switch Circuit Malfunction
B1780	Front Occupant Classification Sensor LH Circuit Malfunction
B1782	Rear Occupant Classification Sensor LH Circuit Malfunction
B1785	Front Occupant Classification Sensor LH Collision Detection
B1787	Rear Occupant Classification Sensor LH Collision Detection
B1795	Occupant Classification ECU Malfunction
B1798	Yaw Rate Sensor Module Malfunction
B1799	Vehicle Stability Control ECU Malfunction
U0125	Lost Communication with Multi-axis Acceleration Sensor Module
U0129	Lost Communication with Brake System Control Module

Dtc Check / Clear

DTC CHECK / CLEAR

DTC CHECK

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Occupant Detection / Trouble Codes.

Body Electrical > Occupant Detection > Trouble Codes

(f) Check for DTCs by following the prompts on the Techstream screen.

HINT:

Refer to the Techstream operator's manual for further details.

DTC CLEAR

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Occupant Detection / Trouble Codes.

Body Electrical > Occupant Detection > Clear DTCs

(f) Clear the DTCs by following the prompts on the Techstream screen.

HINT:

Refer to the Techstream operator's manual for further details.

Fail-safe Chart

FAIL-SAFE CHART

FAIL-SAFE FUNCTION

(a) The following chart shows the status of the front passenger SRS items and passenger airbag ON/OFF indicator operation under each condition.

The passenger airbag ON/OFF indicator ("ON" and "OFF") comes on for approximately 4 seconds, then turns off for approximately 2 seconds.
Approximately 6 seconds after the engine switch is turned on (IG), the passenger airbag ON/OFF indicator will indicate "ON" or "OFF" depending on the following conditions.

Condition	Passenger Airbag ON/OFF Indicator		Front Passenger SRS Item
Condition	ON Indicator	OFF Indicator	Instrument Panel Passenger Airbag Assembly	Lower No. 2 Instrument Panel Airbag Assembly	Front Seat Airbag Assembly RH	Curtain Shield Airbag Assembly RH	Front Seat Outer Belt Assembly RH
○: Deployable X: Not deployable 1: The system judges a person of average adult weight or more as an adult. If a smaller adult sits in the front passenger seat, the system may not recognize them as an adult depending on their physique and posture. 2: The system may not recognize a child or a child in a child restrain system as a child depending on factors such as the positioning of the child restraint system or the child's physique or posture.
Adult*1 is seated	ON	OFF	○	○	○	○	○
Child*2 is seated	ON or OFF*2	OFF or ON*2	○ or X*2	○ or X*2	○	○	○
Child restraint system is installed	OFF	ON	X	X	○	○	○
Vacant	OFF	ON	X	X	○	○	○
Failure	OFF	ON	X	X	○	○	○

How To Proceed With Troubleshooting

CAUTION / NOTICE / HINT

HINT:

Use the following procedure to troubleshoot the occupant classification system.
*: Use the Techstream.

PROCEDURE

1.	VEHICLE BROUGHT TO WORKSHOP

2.	CUSTOMER PROBLEM ANALYSIS

(a) Confirm problem symptoms.

Click here

3.	CHECK CAN COMMUNICATION SYSTEM*

(a) Using the Techstream, check if the CAN communication system is functioning normally.

OK:

CAN communication system is functioning normally.

HINT:

Refer to Communication Bus Check in CAN Communication System.
Click here
The occupant detection ECU is connected to the CAN communication system. Therefore, before starting troubleshooting, make sure to check that there are no malfunctions in the CAN communication system.

GO TO CAN COMMUNICATION SYSTEM

4.	PASSENGER AIRBAG ON/OFF INDICATOR CHECK

(a) Refer to Diagnosis System.

Click here

5.	DTC CHECK (Present and History DTCs)*

(a) Refer to DTC Check / Clear.

Click here

OK:

DTCs are not output.

GO TO PROBLEM SYMPTOMS TABLE

6.	DIAGNOSTIC TROUBLE CODE CHART

(a) Refer to Diagnostic Trouble Code Chart.

Click here

7.	CIRCUIT INSPECTION*

REPAIR

9.	CLEAR DTCS (Present and History DTCs)*

(a) Refer to DTC Check / Clear.

Click here

10.	DTC CHECK*

(a) Refer to DTC Check / Clear.

Click here

OK:

DTCs are not output.

GO TO STEP 6

11.	SYMPTOM SIMULATION

(a) Check the passenger airbag ON/OFF indicator condition.

12.	CONFIRMATION TEST

END

Initialization

INITIALIZATION

DESCRIPTION

(a) Zero point of the occupant classification sensors may deviate in the following situations. To ensure sensor accuracy, be sure to perform Zero Point Calibration.

The occupant detection ECU is replaced.
HINT:

As the zero point is not automatically stored in a new occupant detection ECU, it is necessary to perform zero point calibration after replacing the occupant detection ECU.
Accessories (seatback tray, seat cover, etc.) are installed.
HINT:

As the weight of accessories will be added to the weight of the occupant, the system will not be able to perform classification accurately.
The front passenger seat is removed from the vehicle.
HINT:

As the seat frame will warp slightly when the bolts that are used to install the front passenger seat are tightened, the load applied to the occupant classification sensors will change and the system will not be able to perform classification accurately.
Any of the bolts that are used to install the front passenger seat are removed and reinstalled.
HINT:

As the seat frame will warp slightly when the bolts that are used to install the front passenger seat are tightened, the load applied to the occupant classification sensors will change and the system will not be able to perform classification accurately.
The passenger airbag ON/OFF indicator ("ON") illuminates when the front passenger seat is not occupied.
HINT:

If any load or pressure is applied to the occupant classification sensors, the system will not be able to perform classification accurately.
An occupant classification sensor collision detection DTC is output due to an accident or a collision.

NOTICE:

Make sure that the front passenger seat is not occupied before performing the operation.

ZERO POINT CALIBRATION

(a) Zero point calibration procedure

(1) Check that all of the following conditions are met:

The vehicle is parked on a level surface.
No objects are placed on the front passenger seat.
No objects are touching the front passenger seat.

(2) Adjust the seat position according to the table below.

Adjustment Item	Position
Slide Direction	50 mm (1.97 in.) from rearmost position
Headrest Height	Lowest position
Recline Angle	Upright position
Front Tilt Height	Lowest position
Seat Lifter Height	Lowest position

(3) Turn the engine switch off.

(4) Connect the Techstream to the DLC3.

(5) Turn the engine switch on (IG).

(6) Turn the Techstream on.

(7) Enter the following menus: Body Electrical / Occupant Detection / Utility / Zero Point Calibration.

Body Electrical > Occupant Detection > Utility

Tester Display
Zero Point Calibration

(8) Perform zero point calibration by following the prompts on the Techstream screen.

OK:

"Zero Point Calibration is complete." is displayed.

HINT:

Refer to the Techstream operator's manual for further details.
If zero point calibration does not complete normally, perform this procedure again. If zero point calibration cannot be completed normally, replace the separate type front seat cushion spring assembly RH.

Parts Location

PARTS LOCATION

ILLUSTRATION

BRAKE ACTUATOR ASSEMBLY

- SKID CONTROL ECU

ILLUSTRATION

*1	- ACCELERATION SENSOR AIRBAG ECU ASSEMBLY	*2	OCCUPANT DETECTION ECU
*3	RADIO AND DISPLAY RECEIVER ASSEMBLY - PASSENGER AIRBAG ON/OFF INDICATOR	*4	FRONT SEAT INNER BELT ASSEMBLY RH - FRONT PASSENGER SIDE BUCKLE SWITCH
*5	SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY RH	*6	FRONT OCCUPANT CLASSIFICATION SENSOR LH
*7	REAR OCCUPANT CLASSIFICATION SENSOR LH	*8	COMBINATION METER ASSEMBLY - SRS WARNING LIGHT
*9	DLC3	*10	INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - A/BAG-IG2 FUSE - ECU-IG1 NO. 4 FUSE

Precaution

PRECAUTION

PRECAUTION FOR DISCONNECTING CABLE FROM NEGATIVE BATTERY TERMINAL

NOTICE:

When disconnecting the cable from the negative (-) battery terminal, initialize the following systems after the cable is reconnected:

System	See Procedure
Lane Departure Alert System (w/ Steering Control)
Intelligent Clearance Sonar System
Parking Assist Monitor System
Panoramic View Monitor System
Pre-collision System
Lighting System (for Gasoline Model with Cornering Light)

GENERAL PRECAUTION

(a) The following conditions may be interpreted as a malfunction even though they are normal operation:

An object is placed on the front passenger seat and the system judges that an adult is seated. As the occupant classification system detects and classifies occupants based on weight, the system may detect an object placed on the seat cushion as an adult passenger depending on its weight.
Pressure is applied to the front passenger seat and the system judges that an adult is seated. As the occupant classification system detects and classifies occupants based on weight, the system may detect an adult passenger if pressure is applied to the seat cushion by hands, etc.
Illumination of the passenger airbag ON/OFF indicator does not change immediately after a passenger is seated or leaves the vehicle. To prevent the classification judgment from changing when a passenger changes their seating posture, a certain amount of time is required to detect and classify an occupant when the calculated weight changes. Therefore, there will be a time lag between when a passenger is seated or leaves the vehicle and when the system detects the occupant.

(b) Zero point of the occupant classification sensors may deviate in the following situations. To ensure sensor accuracy, be sure to perform Zero Point Calibration.

The occupant detection ECU is replaced.
HINT:

As the zero point is not automatically stored in a new occupant detection ECU, it is necessary to perform zero point calibration after replacing the occupant detection ECU.
Accessories (seatback tray, seat cover, etc.) are installed.
HINT:

As the weight of accessories will be added to the weight of the occupant, the system will not be able to perform classification accurately.
The front passenger seat is removed from the vehicle.
HINT:

As the seat frame will warp slightly when the bolts that are used to install the front passenger seat are tightened, the load applied to the occupant classification sensors will change and the system will not be able to perform classification accurately.
Any of the bolts that are used to install the front passenger seat are removed and reinstalled.
HINT:

As the seat frame will warp slightly when the bolts that are used to install the front passenger seat are tightened, the load applied to the occupant classification sensors will change and the system will not be able to perform classification accurately.
The passenger airbag ON/OFF indicator ("ON") illuminates when the front passenger seat is not occupied.
HINT:

If any load or pressure is applied to the occupant classification sensors, the system will not be able to perform classification accurately.
An occupant classification sensor collision detection DTC is output due to an accident or a collision.

Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

HINT:

Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
Inspect the fuses and relays related to this system before inspecting the suspected areas below.

Occupant Classification System

Symptom

Suspected Area

Link

The passenger airbag ON/OFF indicator indication differs from the indication patterns of "Indicator Operation"

Click here

Airbag system
Zero point calibration
Wire harness
Front seat inner belt assembly RH
Occupant detection ECU

System Description

SYSTEM DESCRIPTION

GENERAL

(a) The occupant detection ECU estimates the weight of an occupant based on signals received from the 2 occupant classification sensors. The occupant detection ECU determines whether the front passenger seat is occupied and classifies the occupant based on the estimated weight, front passenger side buckle switch state, acceleration sensor signal and vehicle speed signal. The result determined by the occupant detection ECU is sent to the airbag ECU assembly via CAN communication.

(b) The airbag ECU assembly controls the operation of the passenger airbag ON/OFF indicator and restricts the operation of the instrument panel passenger airbag assembly and lower No. 2 instrument panel airbag assembly.

System Diagram

SYSTEM DIAGRAM

Communication Table

Transmitting ECU

(Transmitter)

Receiving ECU

Signal

Communication Method

Airbag ECU Assembly

Occupant Detection ECU

Crash detection signal
Acceleration signal

CAN

Skid Control ECU (Brake Actuator Assembly)

Occupant Detection ECU

Vehicle speed signal

Occupant Detection ECU

Airbag ECU Assembly

Occupant classification system failure signal
Occupant classification system zero point error signal
Occupant state for front passenger signal
Buckle switch state of front passenger signal

Terminals Of Ecu

TERMINALS OF ECU

OCCUPANT DETECTION ECU

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
R8-1 (SVC1) - R8-5 (SGD1)	R - G	Front occupant classification sensor LH power supply	Engine switch on (IG)	11 to 14 V
R8-2 (SVC3) - R8-6 (SGD3)	GR - W	Rear occupant classification sensor LH power supply	Engine switch on (IG)	11 to 14 V
R8-3 (SIG1) - R8-5 (SGD1)	P - G	Front occupant classification sensor LH signal	Engine switch on (IG)	Pulse generation
R8-4 (SIG3) - R8-6 (SGD3)	Y - W	Rear occupant classification sensor LH signal	Engine switch on (IG)	Pulse generation
R8-5 (SGD1) - R7-10 (GND)	G - W-B	Front occupant classification sensor LH ground	Always	Below 1 V
R8-6 (SGD3) - R7-10 (GND)	W - W-B	Rear occupant classification sensor LH ground	Always	Below 1 V
R7-4 (CANN) - R7-10 (GND)	W - W-B	CAN communication line	Engine switch on (IG)	Pulse generation
R7-5 (CANP) - R7-10 (GND)	L - W-B	CAN communication line	Engine switch on (IG)	Pulse generation
R7-6 (IG) - R7-10 (GND)	B - W-B	Power source	Engine switch on (IG)	11 to 14 V
R7-7 (BSW) - R7-9 (BGND)	G - P	Front passenger side buckle switch signal	Always	Pulse generation
R7-9 (BGND) - R7-10 (GND)	P - W-B	Front passenger side buckle switch ground	Always	Below 1 V
R7-10 (GND) - Body ground	W-B - Body ground	Ground	Always	Below 1 V

Trouble in Passenger Airbag ON/OFF Indicator

DESCRIPTION

The occupant classification system detects the front passenger seat condition. It then displays the instrument panel passenger airbag assembly and lower No. 2 instrument panel airbag assembly condition (activated/not activated) using the passenger airbag ON/OFF indicator.

HINT:

Approximately 6 seconds after the engine switch is turned on (IG), the passenger airbag ON/OFF indicator will indicate ON/OFF depending on the following conditions.

Front Passenger Seat Condition	Passenger Airbag ON/OFF Indicator		SRS Warning Light
Front Passenger Seat Condition	ON Indicator	OFF Indicator	SRS Warning Light
Vacant	OFF	ON	OFF
Adult*1 is seated	ON	OFF	OFF
Child*2 is seated	ON or OFF*2	OFF or ON*2	OFF
Child restraint system is installed	OFF	ON	OFF
Occupant classification system failure	OFF	ON	ON

*1: The system judges a person of average adult weight or more as an adult. If a smaller adult sits in the front passenger seat, the system may not recognize them as an adult depending on their physique and posture.
*2: The system may not recognize a child or a child in a child restrain system as a child depending on factors such as the positioning of the child restraint system or the child's physique or posture.

CAUTION / NOTICE / HINT

NOTICE:

After turning the engine 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
Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.	CHECK SRS WARNING LIGHT

(a) Turn the engine switch on (IG), and check the SRS warning light condition.

OK:

After the primary check period, the SRS warning light turns off.

HINT:

The primary check is performed for approximately 6 seconds after the engine switch is turned on (IG).

GO TO AIRBAG SYSTEM

2.	PERFORM ZERO POINT CALIBRATION

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

Click here

OK:

"Zero Point Calibration is complete." is displayed.

END

3.	RETIGHTEN FRONT SEAT ASSEMBLY RH BOLT

(a) Loosen the 4 installation bolts of the front seat assembly RH.

(b) Tighten the 4 installation bolts of the front seat assembly RH to the specified torque.

Click here

4.	PERFORM ZERO POINT CALIBRATION

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

Click here

OK:

"Zero Point Calibration is complete." is displayed.

END

5.	READ VALUE USING TECHSTREAM

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Occupant Detection / Data List.

(f) Read the Data List according to the display on the Techstream.

Body Electrical > Occupant Detection > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Passenger Buckle SW

Front passenger side buckle switch

NG, Set or Unset

Set: Front passenger seat belt is fastened

Unset: Front passenger seat belt is not fastened

"NG" will be displayed immediately after the engine switch is turned on (IG).

Body Electrical > Occupant Detection > Data List

Tester Display
Passenger Buckle SW

OK:

The Techstream display changes correctly in accordance with the operation of the front passenger side buckle switch.

GO TO STEP 9

6.	CHECK CONNECTORS

(a) Turn the engine switch off.

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

(c) Disconnect the connectors from the occupant detection ECU, front occupant classification sensor LH and rear occupant classification sensor LH.

(d) 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

7.	REPLACE OCCUPANT DETECTION ECU

(a) Connect the connectors to the front occupant classification sensor LH and rear occupant classification sensor LH.

(b) Replace the occupant detection ECU.

Click here

8.	PERFORM ZERO POINT CALIBRATION

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

Click here

END

9.	CHECK CONNECTORS

(a) Turn the engine switch off.

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

(d) 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

10.	REPLACE FRONT SEAT INNER BELT ASSEMBLY RH

(a) Turn the engine 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

END

Lost Communication with Multi-axis Acceleration Sensor Module (U0125,U0129)

DESCRIPTION

The occupant detection ECU sends/receives signals to/from each ECU via CAN communication.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
U0125	Lost Communication with Multi-axis Acceleration Sensor Module	CAN communication error between occupant detection ECU and acceleration sensor (CAN communication system malfunction)	CAN communication system
U0129	Lost Communication with Brake System Control Module	CAN communication error between occupant detection ECU and skid control ECU (CAN communication system malfunction)	CAN communication system

CAUTION / NOTICE / HINT

Refer to troubleshooting in CAN Communication System.

Click here

PROCEDURE

1.	GO TO CAN COMMUNICATION SYSTEM

(a) Go to CAN communication system.

Click here

END

Occupant Classification Ecu

Occupant Classification System(for Hv Model)

See More:

Toyota Avalon (XX50) 2019-2022 Owners Manual > Steps to take in an emergency: If you think something is wrong
If you notice any of the following symptoms, your vehicle probably needs adjustment or repair. Contact your Toyota dealer as soon as possible. Visible symptoms Fluid leaks under the vehicle. (Water dripping from the air conditioning after use is normal.) Flat-looking tires or uneven tire wear Engin ...