DTC B1821: Open In Side Airbag RH

Diagnosis start condition: 

When the ignition voltage is 10 - 16 V.

DTC detecting condition: 

• Side airbag harness RH circuit is open.
• Side airbag module 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 side airbag module RH.

   Is there poor contact?

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

   No  : Go to  2.

2. CHECK AIRBAG REAR HARNESS (SIDE AIRBAG MODULE HARNESS RH) (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 (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 (AB87) from side airbag module RH.
   6. Disconnect the connector (AB91) from curtain airbag module RH.
   7. Disconnect the connectors (AB41, AB42, AB43) from airbag control module.
   8. Using test harness AT, measure the resistance between terminals of connector (AB87) of side airbag module RH.
      CAUTION:

      Connect the test harness AT terminal to the connector (AB87) terminal and contact a tester to the test harness AT. Two sets of test harness AT are required. 

      Connector & terminal 

      (AB87) No. 1 - (AB87) 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 connectors other than side airbag module RH connector (AB87).
   2. Using test harness AT, short the terminals No. 1 and No. 2 of connector (AB87).
   3. Install the ground terminal to the battery sensor and turn the ignition switch to ON. Ref. to REPAIR CONTENTS>NOTE>BATTERY
   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 B1821 displayed? (Current code)

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

   No  : Replace the side airbag module RH. Ref. to AIRBAG SYSTEM>SIDE AIRBAG MODULE>REMOVAL