DTC B1927: Short In Rear P/T LH (To Ground)

Diagnosis start condition: 

When the ignition voltage is 10 - 16 V.

DTC detecting condition: 

• Rear pretensioner harness LH circuit is shorted to ground.
• Rear seatbelt pretensioner LH is faulty.
• Airbag control module is faulty.

Failure detection pattern: 

• Detection by a single system (Primary Failure)

Warning light/indicator light: 

• Airbag warning light◦

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 Rear seatbelt pretensioner LH.

   Is there poor contact?

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

   No:  GO TO  2.

2. CHECK Rear seatbelt 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>NOTE>BATTERY .
   2. Disconnect the connector (AB100) from rear seat belt pretensioner LH.
   3. Connect the connector (1N) in the test harness N to the connector (AB100).
   4. Connect the airbag resistor to the connector (2N) of test harness N.
   5. Install 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 B1927 displayed? (Current code)

   Yes:  GO TO  3.

   No:  Replace Rear seatbelt pretensioner LH. Ref. to SEAT BELT SYSTEM>REAR SEAT BELT .

3. CHECK AIRBAG REAR HARNESS (REAR PRETENSIONER HARNESS LH) (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 (AB94) from seat belt pretensioner LH.
   3. Disconnect the connector (AB96) from lap seat belt pretensioner LH.
   4. Disconnect the connector (AB92) from curtain airbag module LH.
   5. Disconnect the connector (AB88) from side airbag module LH.
   6. Disconnect the airbag resistor from test harness N.
   7. Disconnect the connectors (AB41, AB42, AB43) from airbag control module.
   8. Connect the connector (1BF) in the test harness BF to the connectors (AB41, AB42, AB43).
   9. Measure the resistance between connector (7BF) in the test harness BF and chassis ground.

      Connector & terminal 

      (7BF) No. 12 - Chassis ground:

      (7BF) No. 18 - Chassis ground:

   Is the resistance 1 MΩ or more?

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

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