Toyota Venza: Passenger Side Buckle Switch Circuit Malfunction (B1771)

Toyota Venza Service Manual / Supplemental Restraint Systems / Occupant Classification System / Passenger Side Buckle Switch Circuit Malfunction (B1771)

DESCRIPTION

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

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

Troubleshoot DTC B1771 first if DTCs B1771 and B1795 are output simultaneously.

DTC No.	DTC Detection Condition	Trouble Area
B1771	The occupant classification ECU receives a line short circuit signal, an open circuit signal, a short circuit to ground signal or a short circuit to B+ signal in the passenger side buckle switch circuit for 2 seconds. Passenger side buckle switch malfunction Occupant classification ECU malfunction	Front seat inner belt assembly RH (Passenger side buckle switch) Occupant classification ECU Front seat wire RH (for Power seat) No. 2 Floor wire (for Manual seat)

HINT:

When DTC B1650/32 is detected as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant classification ECU. When DTC B1771 is output, perform troubleshooting for the DTC.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

HINT:

If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger seat installation bolts to see under the seat cushion.
In the above case, 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 classification ECU and front seat inner belt assembly RH.

OK:

The connectors are properly connected.

HINT:

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

(d) Disconnect the connectors from the occupant classification ECU and front seat inner belt assembly RH.

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

OK:

The terminals are not deformed or damaged.

Result

Result	Proceed to
OK	A
NG (for Power seat)	B
NG (for Manual seat)	C

REPLACE FRONT SEAT WIRE RH

REPLACE NO. 2 FLOOR WIRE

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

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

(b) Turn the ignition switch to ON.

Standard Voltage:

for Power Seat

Tester Connection	Switch Condition	Specified Condition
S12-9 (BSW) - Body ground	Ignition switch ON	Below 1 V
S12-5 (BGND) - Body ground	Ignition switch ON	Below 1 V

for Manual Seat

Tester Connection	Switch Condition	Specified Condition
M14-9 (BSW) - Body ground	Ignition switch ON	Below 1 V
M14-5 (BGND) - Body ground	Ignition switch ON	Below 1 V

Result

Result	Proceed to
OK	A
NG (for Power seat)	B
NG (for Manual seat)	C

Text in Illustration

*1	Front Seat Inner Belt Assembly RH
*2	Occupant Classification ECU
*3	Front Seat Wire RH
*4	Front view of wire harness connector (to Occupant Classification ECU)
*5	Connector B
*6	for Power Seat
*7	for Manual Seat

REPLACE FRONT SEAT WIRE RH

REPLACE NO. 2 FLOOR WIRE

3.	CHECK FRONT SEAT WIRE RH (OPEN)

(a) Turn the ignition switch off.

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

NOTICE:

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

SST: 09843-18040

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

Standard Resistance:

for Power Seat

Tester Connection	Condition	Specified Condition
S12-9 (BSW) - S12-5 (BGND)	Always	Below 1 Ω

for Manual Seat

Tester Connection	Condition	Specified Condition
M14-9 (BSW) - M14-5 (BGND)	Always	Below 1 Ω

Result

Result	Proceed to
OK	A
NG (for Power seat)	B
NG (for Manual seat)	C

Text in Illustration

*1	Front Seat Inner Belt Assembly RH	*2	Occupant Classification ECU
*3	Front Seat Wire RH	*4	Front view of wire harness connector (to Occupant Classification ECU)
*5	Front view of wire harness connector (to Front Seat Inner Belt Assembly RH)	*6	Connector B
*7	Connector C	*8	for Power Seat
*9	for Manual Seat	-	-

REPLACE FRONT SEAT WIRE RH

REPLACE NO. 2 FLOOR WIRE

4.	CHECK FRONT SEAT WIRE RH (SHORT)

(a) Disconnect SST from connector C.

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

Standard Resistance:

for Power Seat

Tester Connection	Condition	Specified Condition
S12-9 (BSW) - S12-5 (BGND)	Always	1 MΩ or higher

for Manual Seat

Tester Connection	Condition	Specified Condition
M14-9 (BSW) - M14-5 (BGND)	Always	1 MΩ or higher

Result

Result	Proceed to
OK	A
NG (for Power seat)	B
NG (for Manual seat)	C

Text in Illustration

*1	Front Seat Inner Belt Assembly RH
*2	Occupant Classification ECU
*3	Front Seat Wire RH
*4	Front view of wire harness connector (to Occupant Classification ECU)
*5	Connector B
*6	for Power Seat
*7	for Manual Seat

REPLACE FRONT SEAT WIRE RH

REPLACE NO. 2 FLOOR WIRE

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

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

Standard Resistance:

for Power Seat

Tester Connection	Condition	Specified Condition
S12-9 (BSW) - Body ground	Always	1 MΩ or higher
S12-5 (BGND) - Body ground	Always	1 MΩ or higher

for Manual Seat

Tester Connection	Condition	Specified Condition
M14-9 (BSW) - Body ground	Always	1 MΩ or higher
M14-5 (BGND) - Body ground	Always	1 MΩ or higher

Result

Result	Proceed to
OK	A
NG (for Power seat)	B
NG (for Manual seat)	C

Text in Illustration

*1	Front Seat Inner Belt Assembly RH
*2	Occupant Classification ECU
*3	Front Seat Wire RH
*4	Front view of wire harness connector (to Occupant Classification ECU)
*5	Connector B
*6	for Power Seat
*7	for Manual Seat

REPLACE FRONT SEAT WIRE RH

REPLACE NO. 2 FLOOR WIRE

CHECK DTC

(a) Connect the connectors to the occupant classification 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 classification ECU (See page ).

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

(f) Turn the ignition switch off.

(g) Turn the ignition switch to ON.

(h) Check for DTCs (See page ).

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.

USE SIMULATION METHOD TO CHECK

7.	REPLACE FRONT SEAT INNER BELT ASSEMBLY RH

(a) Turn the ignition switch off.

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

HINT:

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

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

(e) Turn the ignition switch to ON.

(f) Clear the DTCs stored in the occupant classification ECU (See page ).

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

(h) Turn the ignition switch off.

(i) Turn the ignition switch to ON.

(j) Check for DTCs (See page ).

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.

END

8.	REPLACE OCCUPANT CLASSIFICATION ECU

(a) Turn the ignition switch off.

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

9.	PERFORM ZERO POINT CALIBRATION

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

(b) Connect the Techstream to the DLC3.

(d) Using the Techstream, perform Zero Point Calibration (See page ).

OK:

"Zero Point Calibration is complete." is displayed.

10.	PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform Sensitivity Check (See page ).

Standard:

27 to 33 kg (59.5 to 72.8 lb)

END

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