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 (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, side airbag module RH and the side airbag sensor 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>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 (AB26) from seat belt pretensioner RH.
   3. Disconnect the connector (AB30) from the lap seat belt pretensioner RH.
   4. Disconnect the connector (AB24) from side airbag module RH.
   5. Disconnect the connector (AB33) from curtain airbag module RH.
   6. Disconnect the connectors (AB6, AB17, AB18) from airbag control module.
   7. Measure the resistance between terminals of connector (AB24) of side airbag module RH.
      CAUTION: Connect the test harness AT terminal to the connector (AB24) terminal and contact a tester to the test harness AT. Two sets of test harness AT are required.

      Connector & terminal 

      (AB24) No. 1 - (AB24) 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 (AB24).
   2. Using test harness AT, short the terminals No. 1 and No. 2 of connector (AB24).
   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. 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 malfunction)

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

   No  : Go to  4.

4. CHECK SIDE AIRBAG 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>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 B1821 displayed? (Current malfunction)

   Yes  : Replace the side airbag module RH. Ref. to AIRBAG SYSTEM>SIDE AIRBAG MODULE>REMOVAL

   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.