DTC B1903: Short In Front P/T RH (To +B)

Diagnosis start condition: 

When the ignition voltage is 10 - 16 V.

DTC detecting condition: 

• Seat belt pretensioner harness RH circuit is shorted to power supply.
• Seat belt pretensioner RH 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 RH.

   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 RH) (SHORTED TO POWER SUPPLY)  .
   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 (AB93) from seat belt pretensioner RH.
   3. Disconnect the connector (AB95) from the lap seat belt pretensioner RH.
   4. Disconnect the connector (AB99) from Rear seatbelt pretensioner RH.
   5. Disconnect the connector (AB91) from curtain airbag module RH.
   6. Disconnect the connector (AB87) from side airbag module RH.
   7. Disconnect the connectors (AB41, AB42, AB43) from airbag control module.
   8. Install the ground terminal to the battery sensor and turn the ignition switch to ON. Ref. to REPAIR CONTENTS>NOTE>BATTERY
   9. Using a probe, measure the voltage between the connector (AB93) and chassis ground. Ref. to AIRBAG (DIAGNOSTICS)>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE PROBE 
      CAUTION:

      When measuring, 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 

      (AB93) No. 1 (+) - Chassis ground (-):

      (AB93) No. 2 (+) - Chassis ground (-):

   Is the voltage less than 1 V?

   Yes  : Go to  3.

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

3. CHECK AIRBAG CONTROL MODULE  .
   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. Connect all the connectors other than (AB93) of seat belt pretensioner RH.
   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 B1903 displayed? (Current code)

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

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