Toyota Venza: Seat Belt Buckle Switch LH Circuit Malfunction (B1656/38)

DESCRIPTION

The seat belt buckle switch LH circuit consists of the center airbag sensor assembly and front seat inner belt assembly LH.

DTC B1656/38 is stored when a malfunction is detected in the seat belt buckle switch LH circuit.

DTC No.	DTC Detection Condition	Trouble Area
B1656/38	The center airbag sensor assembly 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 seat belt buckle switch LH circuit. Front seat inner belt assembly LH malfunction Center airbag sensor assembly malfunction	Floor wire Front seat inner belt assembly LH (Seat belt buckle switch LH) Center airbag sensor assembly

WIRING DIAGRAM

PROCEDURE

1.	CHECK CONNECTORS

(a) Turn the ignition switch off.

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

(c) Check that the connectors are properly connected to the center airbag sensor assembly and front seat inner belt assembly LH.

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 center airbag sensor assembly and front seat inner belt assembly LH.

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

OK:

The terminals are not deformed or damaged.

NG

REPLACE FLOOR WIRE

OK

2.	CHECK FLOOR WIRE (OPEN)

(a) Using SST, connect terminals 10 (LBE+) and 18 (LBE-) of connector B.

NOTICE:

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

SST: 09843-18040

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
L19-1 (LBE+) - L19-3 (LBE-)	Always	Below 1 Ω

Text in Illustration

*1	Front Seat Inner Belt Assembly LH	*2	Center Airbag Sensor Assembly
*3	Floor Wire	*4	Front view of wire harness connector (to Center Airbag Sensor Assembly)
*5	Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)	*6	Connector B
*7	Connector C	-	-

NG

REPLACE FLOOR WIRE

OK

3.	CHECK FLOOR WIRE (SHORT)

(a) Disconnect SST from connector B.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
L19-1 (LBE+) - L19-3 (LBE-)	Always	1 MΩ or higher

Text in Illustration

*1	Front Seat Inner Belt Assembly LH
*2	Center Airbag Sensor Assembly
*3	Floor Wire
*4	Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)
*5	Connector C

NG

REPLACE FLOOR WIRE

OK

4.	CHECK FLOOR WIRE (SHORT TO B+)

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

(b) Turn the ignition switch to ON.

(c) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
L19-1 (LBE+) - Body ground	Ignition switch ON	Below 1 V
L19-3 (LBE-) - Body ground	Ignition switch ON	Below 1 V

Text in Illustration

*1	Front Seat Inner Belt Assembly LH
*2	Center Airbag Sensor Assembly
*3	Floor Wire
*4	Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)
*5	Connector C

NG

REPLACE FLOOR WIRE

OK

5.	CHECK FLOOR WIRE (SHORT TO GROUND)

(a) Turn the ignition switch off.

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

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
L19-1 (LBE+) - Body ground	Always	1 MΩ or higher
L19-3 (LBE-) - Body ground	Always	1 MΩ or higher

Text in Illustration

*1	Front Seat Inner Belt Assembly LH
*2	Center Airbag Sensor Assembly
*3	Floor Wire
*4	Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)
*5	Connector C

NG

REPLACE FLOOR WIRE

OK

6.	CHECK FRONT SEAT INNER BELT ASSEMBLY LH

(a) Connect the connectors to the center airbag sensor assembly and front seat inner belt assembly LH.

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

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

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

(e) Turn the ignition switch off.

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

(g) Check for DTCs (See page ).

OK:

DTC B1656/38 is not output.

Text in Illustration

*1	Front Seat Inner Belt Assembly LH
*2	Center Airbag Sensor Assembly

HINT:

Codes other than DTC B1656/38 may be output at this time, but they are not related to this check.

OK

USE SIMULATION METHOD TO CHECK

NG

7.	REPLACE FRONT SEAT INNER BELT ASSEMBLY LH

(a) Turn the ignition switch off.

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

(c) Replace the front seat inner belt assembly LH with a known good part (See page ).

HINT:

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

NEXT

8.	CHECK CENTER AIRBAG SENSOR ASSEMBLY

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

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

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

(d) Turn the ignition switch off.

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

(f) Check for DTCs (See page ).

OK:

DTC B1656/38 is not output.

Text in Illustration

*1	Front Seat Inner Belt Assembly LH
*2	Center Airbag Sensor Assembly

HINT:

Codes other than DTC B1656/38 may be output at this time, but they are not related to this check.

OK

END

NG

REPLACE CENTER AIRBAG SENSOR ASSEMBLY