Supplemental Restraint System. Dtc B1656/38 Seat Belt Buckle Switch Lh Circuit Malfunction

Restraints. Lexus Gs430, Gs300. Uzs190 Grs190

Supplemental Restraint System. Lexus Gs430, Gs300. Uzs190 Grs190

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK DTC

CHECK CONNECTION OF CONNECTORS

CHECK FLOOR WIRE NO.2 (OPEN)

CHECK FLOOR WIRE NO.2 (SHORT)

CHECK FLOOR WIRE NO.2 (SHORT TO B+)

CHECK FLOOR WIRE NO.2 (SHORT TO GROUND)

CHECK FRONT SEAT INNER BELT ASSEMBLY LH

REPLACE FRONT SEAT INNER BELT ASSEMBLY LH

CHECK CENTER AIRBAG SENSOR ASSEMBLY

DTC B1656/38 Seat Belt Buckle Switch LH Circuit Malfunction

DESCRIPTION

The seat belt buckle switch LH circuit consists of the center airbag sensor assembly and the front seat inner belt assembly LH.
DTC B1656/38 is recorded when a malfunction is detected in the seat belt buckle switch LH circuit.

DTC No.	DTC Detecting 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 for 2 seconds. Front seat inner belt assembly LH malfunction Center airbag sensor assembly malfunction	Floor wire No.2 Front seat inner belt assembly LH Center airbag sensor assembly

WIRING DIAGRAM

Lexus Gs430, Gs300. Uzs190 Grs190.Supplemental Restraint System.Airbag System.
Dtc
B1656/38 Seat Belt Buckle Switch Lh Circuit Malfunction

INSPECTION PROCEDURE

1.CHECK DTC

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

Clear the DTCs stored in memory (Click here).

Turn the engine switch off.

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

Check the DTCs (Click here).
OK:
DTC B1656/38 is not output.
HINT:
Codes other than DTC B1656/38 may be output at this time, but they are not related to this check.

USE SIMULATION METHOD TO CHECK

NG

2.CHECK CONNECTION OF CONNECTORS

Turn the engine switch off.

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

Check that the connectors are properly connected to the center airbag sensor assembly and the front seat inner belt assembly LH.
OK:
The connectors are connected.

CONNECT CONNECTORS, THEN GO TO STEP 1

OK

3.CHECK FLOOR WIRE NO.2 (OPEN)

Disconnect the connectors from the center airbag sensor assembly and the front seat inner belt assembly LH.

Using a service wire, connect W16-15 (LBE+) and W16-23 (LBE-) of connector "B".
NOTICE:
Do not forcibly insert a service wire into the terminals of the connector when connecting.

Measure the resistance according to the value(s) in the table below.
Resistance:
Tester connection
Condition
Specified condition
W4-1 (LBE+) -
W4-3 (LBE-)
Always
Below 1 Ω

REPAIR OR REPLACE FLOOR WIRE NO.2

OK

4.CHECK FLOOR WIRE NO.2 (SHORT)

Disconnect the service wire from connector "B".

Measure the resistance according to the value(s) in the table below.
Resistance:
Tester connection
Condition
Specified condition
W4-1 (LBE+) -
W4-3 (LBE-)
Always
1 MΩ or higher

REPAIR OR REPLACE FLOOR WIRE NO.2

OK

5.CHECK FLOOR WIRE NO.2 (SHORT TO B+)

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

Turn the engine switch on (IG).

Measure the voltage according to the value(s) in the table below.
Voltage:
Tester connection
Condition
Specified condition
W4-1 (LBE+) -
Body ground
Engine switch on (IG)
Below 1 V
W4-3 (LBE-) -
Body ground
Engine switch on (IG)
Below 1 V

REPAIR OR REPLACE FLOOR WIRE NO.2

OK

6.CHECK FLOOR WIRE NO.2 (SHORT TO GROUND)

Turn the engine switch off.

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

Measure the resistance according to the value(s) in the table below.
Resistance:
Tester connection
Condition
Specified condition
W4-1 (LBE+) -
Body ground
Always
1 MΩ or higher
W4-3 (LBE-) -
Body ground
Always
1 MΩ or higher

REPAIR OR REPLACE FLOOR WIRE NO.2

OK

7.CHECK FRONT SEAT INNER BELT ASSEMBLY LH

Connect the connector to the center airbag sensor assembly and the front seat inner belt assembly LH.

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

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

Clear the DTCs stored in memory (Click here).

Turn the engine switch off.

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

Check the DTCs (Click here).
OK:
DTC B1656/38 is not output.
HINT:
Codes other than DTC B1656/38 may be output at this time, but they are not related to this check.

USE SIMULATION METHOD TO CHECK

NG

8.REPLACE FRONT SEAT INNER BELT ASSEMBLY LH

Turn the engine switch off.

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

Replace the front seat inner belt assembly LH (Click here).
HINT:
Perform the inspection using parts from a normal vehicle if possible.

NEXT

9.CHECK CENTER AIRBAG SENSOR ASSEMBLY

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

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

Clear the DTCs stored in memory (Click here).

Turn the engine switch off.

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

Check the DTCs (Click here).
OK:
DTC B1656/38 is not output.
HINT:
Codes other than DTC B1656/38 may be output at this time, but they are not related to this check.

REPLACE CENTER AIRBAG SENSOR ASSEMBLY

END

Tester connection	Condition	Specified condition
W4-1 (LBE+) - W4-3 (LBE-)	Always	Below 1 Ω