DTC B1656/38: Seat Belt Buckle Switch LH Circuit Malfunction: Procedure

CHECK CONNECTORS
1. Turn the ignition switch off.
2. Disconnect the cable from the negative (-) auxiliary battery terminal.
  WARNING:
  Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.
3. Check that the connectors are properly connected to the 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.
4. Disconnect the connectors from the airbag sensor 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.
NG → REPLACE FLOOR WIRE

OK: Go to next step

CHECK FLOOR WIRE (OPEN)

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

Fig 1: M36 Connectors
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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
M14-2 (LBE+) - M14-1 (LBE-)	Always	Below 1 Ω

Disconnect the service wire from connector B.

TEXT IN ILLUSTRATION

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

NG → REPLACE FLOOR WIRE

OK: Go to next step

CHECK FLOOR WIRE (SHORT)

Fig 2: M14 Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

Standard Resistance

Tester Connection	Condition	Specified Condition
M14-2 (LBE+) - M14-1 (LBE-)	Always	1 MΩ or higher

TEXT IN ILLUSTRATION

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

NG → REPLACE FLOOR WIRE

OK: Go to next step

CHECK FLOOR WIRE (SHORT TO B+)

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

Fig 3: M14 Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Turn the ignition switch to ON (IG).

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

Standard Voltage

Tester Connection	Condition	Specified Condition
M14-2 (LBE+) - Body ground	Ignition switch ON (IG)	Below 1 V
M14-1 (LBE-) - Body ground	Ignition switch ON (IG)	Below 1 V

Turn the ignition switch off.

Disconnect the cable from the negative (-) auxiliary battery terminal.

WARNING:

Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

TEXT IN ILLUSTRATION

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

NG → REPLACE FLOOR WIRE

OK: Go to next step

CHECK FLOOR WIRE (SHORT TO GROUND)

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

Fig 4: M14 Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard Resistance

Tester Connection	Condition	Specified Condition
M14-2 (LBE+) - Body ground	Always	1 MΩ or higher
M14-1 (LBE-) - Body ground	Always	1 MΩ or higher

TEXT IN ILLUSTRATION

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

NG → REPLACE FLOOR WIRE

OK: Go to next step

CHECK DTC

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

Fig 5: Identifying Side Airbag Sensor Assembly Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Connect the cable to the negative (-) auxiliary battery terminal.
Clear the DTCs stored in memory. Refer to DTC CHECK / CLEAR .
Turn the ignition switch off.
Turn the ignition switch to ON (IG), and wait for at least 60 seconds.

Check for DTCs. Refer to DTC CHECK / CLEAR .

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.

TEXT IN ILLUSTRATION

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

NG → See step 7

OK → See step 8

CHECK FRONT SEAT INNER BELT ASSEMBLY LH

Turn the ignition switch off.

Fig 6: Identifying Side Airbag Sensor Assembly Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect the cable from the negative (-) auxiliary battery terminal.
WARNING:
Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.
Replace the front seat inner belt assembly LH with a known good one. Refer to REMOVAL .
HINT:

Perform the following inspection using known good parts from another vehicle if possible.
Connect the cable to the negative (-) auxiliary battery terminal.
Clear the DTCs stored in memory. Refer to DTC CHECK / CLEAR .
Turn the ignition switch off.
Turn the ignition switch to ON (IG), and wait for at least 60 seconds.
Check for DTCs. Refer to DTC CHECK / CLEAR .
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 ignition switch off.
Disconnect the cable from the negative (-) auxiliary battery terminal.

Return the front seat inner belt assembly LH that was installed for testing to its original location. Refer to REMOVAL .

TEXT IN ILLUSTRATION

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

NG → See step 9

OK → See step 10

USE SIMULATION METHOD TO CHECK. Refer to HOW TO PROCEED WITH TROUBLESHOOTING
REPLACE AIRBAG SENSOR ASSEMBLY. Refer to REMOVAL
REPLACE FRONT SEAT INNER BELT ASSEMBLY LH. Refer to REMOVAL