Toyota Tacoma (2015-2018) Service Manual: Seat Belt Buckle Switch LH Circuit Malfunction (B1656/38)

Toyota Tacoma (2015-2018) Service Manual / Supplemental Restraint Systems / Airbag System / Seat Belt Buckle Switch LH Circuit Malfunction (B1656/38)

DESCRIPTION

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

DTC B1655/37 is stored when a malfunction is detected in the seat belt buckle switch LH circuit.

DTC No.	DTC Detection Condition	Trouble Area
B1655/37	The 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 for 2 seconds Front seat inner belt assembly LH malfunction Airbag sensor assembly malfunction	No. 2 floor wire Front seat inner belt assembly LH (Seat belt buckle switch LH) Airbag sensor assembly

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 (See page PROCEDURE ).

PROCEDURE

1.	CHECK CONNECTION OF CONNECTORS

(a) Turn the ignition switch off.

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

OK:

The connectors are properly connected.

CONNECT CONNECTORS

2.	CHECK CONNECTORS

(a) Disconnect the connector from the airbag sensor assembly.

(b) Disconnect the connector from the front seat inner belt assembly LH.

(c) Check that the connectors (on the airbag sensor assembly side and front seat inner belt assembly LH side) are not damaged (See page OK: ).

OK:

The connectors are not deformed or damaged.

Condition	Proceed to
Normal	A
Abnormal	B

REPLACE HARNESS OR CONNECTOR

3.	CHECK NO. 2 FLOOR WIRE (AIRBAG SENSOR ASSEMBLY - FRONT SEAT INNER BELT ASSEMBLY LH)

Text in Illustration

*1	Front Seat Inner Belt Assembly LH	*2	No. 2 Floor Wire
*3	Airbag Sensor Assembly	*4	Connector C
*5	Connector B	*6	Service Wire
*a	Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)	*b	Front view of wire harness connector (to Airbag Sensor Assembly)

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

(b) Turn the ignition switch to ON.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
F20-1 (LBE+) - Body ground	Ignition switch ON	Below 1 V
F20-2 (LBE-) - Body ground	Ignition switch ON	Below 1 V

(d) Turn the ignition switch off.

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

(f) Using a service wire, connect terminals 11 (LBE+) and 12 (LBE-) of connector B.

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
F20-1 (LBE+) - F20-2 (LBE-)	Always	Below 1 Ω

(h) Disconnect the service wire from connector B.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
F20-1 (LBE+) - F20-2 (LBE-)	Always	1 MΩ or Higher
F20-1 (LBE+) - Body ground	Always	1 MΩ or Higher
F20-2 (LBE-) - Body ground	Always	1 MΩ or Higher

REPLACE NO. 2 FLOOR WIRE

4.	CHECK FRONT SEAT INNER BELT ASSEMBLY LH

(a) Connect the connectors to the airbag sensor assembly.

(b) Connect the connector to the front seat inner belt assembly LH.

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

(e) Clear any DTCs stored in the memory (See page (f) Turn the ignition switch off. ).

(f) Turn the ignition switch off.

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

(h) Check for DTCs (See page OK: ).

OK:

DTC B1655/37 is not output.

HINT:

DTCs other than B1655/37 may be output at this time, but they are not related to this check.

REPLACE USE SIMULATION METHOD TO CHECK

5.	CHECK 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.

HINT:

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

6.	CHECK AIRBAG SENSOR ASSEMBLY

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

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

(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: ).

OK:

DTC B1655/37 is not output.

HINT:

DTCs other than B1655/37 may be output at this time, but they are not related to this check.

END

REPLACE AIRBAG SENSOR ASSEMBLY

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