DTC B181C: Short In Passenger Side Airbag Variable Vent Hole Squib Circuit (To Ground)

Diagnosis start condition: 

When the ignition voltage is 10 - 16 V.

DTC detecting condition: 

• Airbag main harness circuit is shorted to ground.
• Airbag module harness (passenger's side) circuit is shorted to ground.
• Passenger's airbag module (variable vent hole) 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 passenger's airbag module (variable vent hole).

   Is there poor contact?

   Yes:  Replace the airbag harness.

   No:  Go to  2.

2. CHECK AIRBAG MAIN HARNESS (PASSENGER'S AIRBAG (VARIABLE VENT HOLE) HARNESS) (SHORTED TO GROUND)  .
   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 (AB2) from the roll connector.
   3. Disconnect the passenger's airbag module connectors (AB9) and (AB27).
   4. Disconnect the connector (AB66) from the driver's knee airbag module.
   5. Disconnect the connectors (AB6, AB17, AB18) from airbag control module.
   6. Measure the resistance between connector (AB27) of the passenger's airbag (variable vent hole) and chassis ground. Ref. to AIRBAG (DIAGNOSTICS)>General Description>PREPARATION TOOL>HOW TO USE PROBE .
      CAUTION: Connect the test harness AT terminal to the connector (AB27) terminal and contact a tester to the test harness AT.

      Connector & terminal 

      (AB27) No. 1 - Chassis ground:

      (AB27) No. 2 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  3.

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

3. CHECK AIRBAG CONTROL MODULE  .
   1. Connect the connectors (AB6, AB17, AB18) and the airbag control module.
   2. Connect the connector (AB2) to the roll connector.
   3. Connect the passenger's airbag module connector (AB9).
   4. Connect the connector (AB66) to the driver's knee airbag module.
   5. Connect the ground terminal to the battery sensor and turn the ignition switch to ON. Ref. to REPAIR CONTENTS>NOTE>BATTERY .
   6. Execute the inspection mode. Ref. to AIRBAG (DIAGNOSTICS)>INSPECTION MODE .
   7. Read the DTC of [Airbag] using the Subaru Select Monitor. Ref. to AIRBAG (DIAGNOSTICS)>Diagnostic Trouble Code (DTC) .

   Is DTC B181C displayed? (Current malfunction)

   Yes:  Replace the airbag control module. Ref. to AIRBAG SYSTEM>Airbag Control Module>REMOVAL .

   No:  Go to  4.

4. CHECK PASSENGER'S AIRBAG MODULE (VARIABLE VENT HOLE)  .
   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 the passenger's airbag module (variable vent hole) connector (AB27).
   3. Connect 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 B181C displayed? (Current malfunction)

   Yes:  Replace the passenger's airbag module. Ref. to AIRBAG SYSTEM>Passenger's 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.