Toyota 4Runner manuals

Toyota 4Runner: Seat Belt Buckle Switch LH Circuit Malfunction (B1656/38)

Toyota 4Runner Service Manual / Vehicle Interior / 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 center airbag sensor and front seat inner belt LH.

DTC B1656/37 is stored when a malfunction is detected in the seat belt buckle switch LH circuit.

DTC Code

DTC Detection Condition

Trouble Area

B1656/38

One of the following conditions is met:

  • The center airbag sensor detects a line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in the seat belt buckle switch LH circuit for 2 seconds.
  • A front seat inner belt LH malfunction.
  • A center airbag sensor malfunction.
  • No. 2 floor wire
  • Front seat inner belt assembly LH (Seat belt buckle switch LH)
  • Center airbag sensor assembly

WIRING DIAGRAM


CAUTION / NOTICE / HINT

NOTICE:

When disconnecting the cable from the negative (-) battery terminal while performing repairs, some systems need to be initialized after the cable is reconnected (See page ).


PROCEDURE

1.

CHECK FOR DTC

(a) Turn the ignition switch to ON.

(b) Clear the DTCs (See page ).


(c) Turn the ignition switch off.

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

(e) Check for DTCs (See page ).


OK:

DTC B1656 is not output.

HINT:

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


OK

USE SIMULATION METHOD TO CHECK


NG

2.

CHECK CONNECTION OF 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 and front seat inner belt LH.

OK:

The connectors are properly connected.


NG

CONNECT CONNECTORS PROPERLY


OK

3.

CHECK CONNECTORS

(a) Disconnect the connectors from the center airbag sensor and front seat inner belt LH.

(b) Check that the connectors (on the center airbag sensor side and front seat inner belt LH side) are not damaged.

OK:

The connectors are not deformed or damaged.

Text in Illustration

*1

Front Seat Inner Belt LH

*2

Center Airbag Sensor



NG

REPLACE NO. 2 FLOOR WIRE


OK

4.

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

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

Text in Illustration

*1

Front Seat Inner Belt LH

*2

Center Airbag Sensor

*3

No. 2 Floor Wire

*4

Connector C

*5

Connector B

-

-

*a

Front view of wire harness connector

(to Front Seat Inner Belt LH)

*b

Rear view of wire harness connector

(to Center Airbag Sensor)

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

O3-2 (LBE+) - Body ground

Ignition switch ON

Below 1 V

O3-1 (LBE-) - Body ground

Ignition switch ON

Below 1 V

(c) Turn the ignition switch off.

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

O3-2 (LBE+) - O1-10 (LBE+)

Always

Below 1 Ω

O3-2 (LBE+) - Body ground

Always

1 MΩ or higher

O3-1 (LBE-) - O1-18 (LBE-)

Always

Below 1 Ω

O3-1 (LBE-) - Body ground

Always

1 MΩ or higher


NG

REPLACE NO. 2 FLOOR WIRE


OK

5.

CHECK FRONT SEAT INNER BELT LH (SEAT BELT BUCKLE SWITCH)

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


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

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

(d) Clear the DTCs (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 is not output.

HINT:

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

Text in Illustration

*1

Front Seat Inner Belt LH

*2

Center Airbag Sensor


OK

USE SIMULATION METHOD TO CHECK


NG

6.

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 LH (See page ).


HINT:

Perform the inspection using parts from a normally functioning vehicle if possible.


NEXT

7.

CHECK CENTER AIRBAG SENSOR

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


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

(c) Clear the DTCs (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 is not output.

HINT:

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

Text in Illustration

*1

Front Seat Inner Belt LH

*2

Center Airbag Sensor


OK

REPLACE FRONT SEAT INNER BELT ASSEMBLY LH


NG

REPLACE CENTER AIRBAG SENSOR ASSEMBLY

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