DTC B1656/38: Seat Belt Buckle Switch LH Circuit Malfunction [10/2014 - ]: Procedure

CHECK CONNECTORS
1. Turn the engine switch off.
2. Disconnect the cable from the negative (-) battery terminal.
  WARNING:
  Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
3. Check that the connectors are properly connected to the airbag ECU assembly and front seat inner belt assembly LH.
  OK
  
  The connectors are properly connected.
  
  HINT:
  
  If the connectors are not properly connected, reconnect the connectors and proceed to the next inspection.
4. Disconnect the connectors from the airbag ECU assembly and front seat inner belt assembly LH.
5. Check that the terminals of the connectors are not damaged.
  OK
  
  The terminals are not deformed or damaged.
Result:

NG

REPLACE FLOOR WIRE

Result:

OK

See step 2

CHECK FLOOR WIRE (OPEN)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TEXT IN ILLUSTRATION

*1	Front Seat Inner Belt Assembly LH
*2	Airbag ECU Assembly
*3	Floor Wire
*4	Service Wire
*a	Front view of wire harness connector (to Airbag ECU Assembly)
*b	Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)

NOTE:

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

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

Standard Resistance

Tester Connection	Condition	Specified Condition
J2-1 (LBE+) - J2-2 (LBE-)	Always	Below 1 Ω

Disconnect the service wire from connector B.

Result:

REPLACE FLOOR WIRE

Result:

See step 3

CHECK FLOOR WIRE (SHORT)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TEXT IN ILLUSTRATION

*1	Front Seat Inner Belt Assembly LH
*2	Airbag ECU Assembly
*3	Floor Wire
*a	Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)

Standard Resistance

Tester Connection	Condition	Specified Condition
J2-1 (LBE+) - J2-2 (LBE-)	Always	1 MΩ or higher

Result:

REPLACE FLOOR WIRE

Result:

See step 4

CHECK FLOOR WIRE (SHORT TO B+)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TEXT IN ILLUSTRATION

*1	Front Seat Inner Belt Assembly LH
*2	Airbag ECU Assembly
*3	Floor Wire
*a	Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)

Turn the engine switch on (IG).

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

Standard Voltage

Tester Connection	Condition	Specified Condition
J2-1 (LBE+) - Body ground	Engine switch on (IG)	Below 1 V
J2-2 (LBE-) - Body ground	Engine switch on (IG)	Below 1 V

Turn the engine switch off.
Disconnect the cable from the negative (-) battery terminal.
WARNING:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

Result:

REPLACE FLOOR WIRE

Result:

See step 5

CHECK FLOOR WIRE (SHORT TO GROUND)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TEXT IN ILLUSTRATION

*1	Front Seat Inner Belt Assembly LH
*2	Airbag ECU Assembly
*3	Floor Wire
*a	Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)

Standard Resistance

Tester Connection	Condition	Specified Condition
J2-1 (LBE+) - Body ground	Always	1 MΩ or higher
J2-2 (LBE-) - Body ground	Always	1 MΩ or higher

Result:

REPLACE FLOOR WIRE

Result:

See step 6

CHECK DTC

Connect the connectors to the airbag ECU assembly and front seat inner belt assembly LH.

TEXT IN ILLUSTRATION

*1	Front Seat Inner Belt Assembly LH
*2	Airbag ECU Assembly

Connect the cable to the negative (-) battery terminal.
Clear the DTCs stored in memory (Refer to DTC CHECK / CLEAR [10/2014 - ] ).
Turn the engine switch off.
Turn the engine switch on (IG), and wait for at least 60 seconds.
Check for DTCs (Refer to DTC CHECK / CLEAR [10/2014 - ] ).
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.

Result:

USE SIMULATION METHOD TO CHECK

(Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2014 - 10/2015] or HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - ] )

Result:

See step 7

CHECK FRONT SEAT INNER BELT ASSEMBLY LH

Turn the engine switch off.

TEXT IN ILLUSTRATION

*1	Front Seat Inner Belt Assembly LH
*2	Airbag ECU Assembly

Disconnect the cable from the negative (-) battery terminal.
WARNING:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
Replace the front seat inner belt assembly LH with a known good one (Refer to REMOVAL [10/2014 - 10/2015] or REMOVAL [10/2015 - ] ).
HINT:

Perform the following inspection using known good parts from another vehicle if possible.
Connect the cable to the negative (-) battery terminal.
Clear the DTCs stored in memory (Refer to DTC CHECK / CLEAR [10/2014 - ] ).
Turn the engine switch off.
Turn the engine switch on (IG), and wait for at least 60 seconds.
Check for DTCs (Refer to DTC CHECK / CLEAR [10/2014 - ] ).
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.
Turn the engine switch off.
Disconnect the cable from the negative (-) battery terminal.
WARNING:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
Restore the front seat inner belt assembly LH that was installed for testing to its original location (Refer to REMOVAL [10/2014 - 10/2015] or REMOVAL [10/2015 - ] ).

Result:

REPLACE FRONT SEAT INNER BELT ASSEMBLY LH

(Refer to REMOVAL [10/2014 - 10/2015] or REMOVAL [10/2015 - ] )

Result:

REPLACE AIRBAG ECU ASSEMBLY

(Refer to REMOVAL [10/2014 - ] )