DTC B1906: Open In Front P/T LH

Diagnosis start condition: 

When the ignition voltage is 10 - 16 V.

DTC detecting condition: 

• Seat belt pretensioner harness LH circuit is open.
• Seat belt pretensioner LH is faulty.
• Airbag control module is faulty.

Wiring diagram: 

Airbag system Ref. to WIRING SYSTEM>AIRBAG SYSTEM>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK POOR CONTACT OF CONNECTORS  .

   Check for poor contact of the connectors between the airbag control module and the seat belt pretensioner LH.

   Is there poor contact?

   Yes  : Replace the airbag rear harness along with body harness.

   No  : Go to  2.

2. CHECK AIRBAG REAR HARNESS (SEAT BELT PRETENSIONER HARNESS LH) (OPEN CIRCUIT)  .
   1. Turn the ignition switch to OFF, and wait for 60 seconds or more after disconnecting the ground terminal from the battery sensor. Ref. to REPAIR CONTENTS>NOTE>BATTERY
   2. Disconnect the connector (AB94) from seat belt pretensioner LH.
   3. Disconnect the connector (AB100) from rear seat belt pretensioner LH.
   4. Disconnect the connector (AB88) from side airbag module LH.
   5. Disconnect the connector (AB92) from curtain airbag module LH.
   6. Disconnect the connectors (AB41, AB42, AB43) from airbag control module.
   7. Using a probe, measure the resistance between the terminals of connector (AB94). Ref. to AIRBAG (DIAGNOSTICS)>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE PROBE 
      CAUTION:

      When measuring the resistance, make sure that the probe is inserted from the back side (harness side) of the connector. Also, do not insert the probe forcibly. 

      Connector & terminal 

      (AB94) No. 1 - (AB94) No. 2:

   Is the resistance less than 10 Ω?

   Yes  : Go to  3.

   No  : Replace the airbag rear harness along with body harness.

3. CHECK AIRBAG CONTROL MODULE  .
   1. Connect all the connectors other than (AB94) of seat belt pretensioner LH.
   2. Using a probe, short the terminals No. 1 and No. 2 of connector (AB94). Ref. to AIRBAG (DIAGNOSTICS)>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE PROBE 
      CAUTION:

      When shorting the terminals, make sure that the probe is inserted from the back side (harness side) of the connector. Also, do not insert the probe forcibly. 

      Connector & terminal 

      (AB94) No. 1 - (AB94) No. 2:

   3. Install the ground terminal to the battery sensor and turn the ignition switch to ON. Ref. to REPAIR CONTENTS>NOTE>BATTERY
   4. Using the Subaru Select Monitor, perform the clear memory of [Airbag]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY
   5. Execute the inspection mode. Ref. to AIRBAG (DIAGNOSTICS)>INSPECTION MODE 
   6. Read the DTC of [Airbag] using the Subaru Select Monitor. Ref. to AIRBAG (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) 

   Is DTC B1906 displayed? (Current code)

   Yes  : Replace the airbag control module. Ref. to AIRBAG SYSTEM>AIRBAG CONTROL MODULE>REMOVAL

   No  : Replace the seat belt pretensioner LH. Ref. to SEAT BELT SYSTEM>FRONT SEAT BELT