DTC B1905: Short 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 shorted.
• Pretensioner LH is faulty.
• Airbag control module is faulty.

Wiring diagram: 

Airbag system Ref. to WIRING SYSTEM (IMPREZA MODEL)>AIRBAG SYSTEM>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>AIRBAG SYSTEM>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>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 (PRETENSIONER HARNESS LH)  .
   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>REPAIR CONTENTS>NOTE>BATTERY .
      NOTE: For the hybrid model, turn the ignition switch to OFF, and wait for 60 seconds or more after disconnecting the ground terminal from the battery.
   2. Disconnect the connector (AB19) from side airbag module LH.
   3. Disconnect the connector (AB31) from curtain airbag module LH.
   4. Disconnect the connector (AB21) from seat belt pretensioner LH.
   5. Disconnect the connectors (AB6, AB17, AB18) from airbag control module.
   6. Connect the connector (1AG) in the test harness AG to the connectors (AB6, AB17, AB18).
   7. Using a probe, measure the resistance between the terminals of connector (AB21). 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 

      (AB21) No. 1 - (AB21) No. 2:

   Is the resistance 1 MΩ or more?

   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 (AB21) of seat belt pretensioner LH.
   2. Install the ground terminal to the battery sensor and turn the ignition switch to ON. Ref. to REPAIR CONTENTS>REPAIR CONTENTS>NOTE>BATTERY .
      NOTE: For the hybrid model, connect the battery ground terminal and turn the ignition switch to ON.
   3. Using the Subaru Select Monitor, perform the clear memory of [Airbag]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
   4. Execute the inspection mode. Ref. to AIRBAG (DIAGNOSTICS)>INSPECTION MODE .
   5. Read the DTC of [Airbag] using the Subaru Select Monitor. Ref. to AIRBAG (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1905 displayed? (Current malfunction)

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

   No  : Go to  4.

4. CHECK SEAT BELT PRETENSIONER LH  .
   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>REPAIR CONTENTS>NOTE>BATTERY .
      NOTE: For the hybrid model, turn the ignition switch to OFF, and wait for 60 seconds or more after disconnecting the ground terminal from the battery.
   2. Connect all connectors.
   3. Install the ground terminal to the battery sensor and turn the ignition switch to ON. Ref. to REPAIR CONTENTS>REPAIR CONTENTS>NOTE>BATTERY .
      NOTE: For the hybrid model, connect the battery ground terminal and turn the ignition switch to ON.
   4. Using the Subaru Select Monitor, perform the clear memory of [Airbag]. Ref. to COMMON (DIAG)>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 B1905 displayed? (Current malfunction)

   Yes  : Replace the seat belt pretensioner LH. Ref. to SEAT BELT SYSTEM>FRONT SEAT BELT .

   No  : Go to  5.

5. CHECK FOR ANY OTHER DTC ON DISPLAY  .

   Read the DTC of [Airbag] using the Subaru Select Monitor. Ref. to AIRBAG (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is any other DTC displayed? (Current malfunction)

   Yes  : Perform the diagnosis for other displayed DTCs. Ref. to AIRBAG (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .

   No  : Finish the diagnosis.