DTC B1904: Short In Front P/T RH

Diagnosis start condition:

When the ignition voltage is 10 - 16 V.

DTC detecting condition:

Short malfunction between seat belt pretensioner harness RH circuit and other circuits

Failure detection pattern:

"Primary" (high-priority diagnosis)

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.

CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to AIRBAG (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION .

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.
CHECK AIRBAG REAR HARNESS (SEAT BELT PRETENSIONER HARNESS RH) (SHORTED BETWEEN LINES) .
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 (AB99) from Rear seatbelt pretensioner RH.
4. Disconnect the connector (AB89) from seat cushion airbag module 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. Connect the connector (1BF) in the test harness BF to the connectors (AB41, AB42, AB43).
9. Using a probe, measure the resistance between the connector (AB93) and all connector terminals in test harness BF. Ref. to AIRBAG (DIAGNOSTICS)>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE PROBE .
  CAUTION: When measuring the resistance, 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 - All terminals in test harness BF (except for (5BF) No. 3):
  
  (AB93) No. 2 - All terminals in test harness BF (except for (5BF) No. 7):
Is the resistance 1 MΩ or more?

Yes: GO TO 3.

No: Replace the airbag rear harness along with body harness.
CHECK AIRBAG CONTROL MODULE .
1. Disconnect the test harness BF from the connectors (AB41, AB42, AB43).
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 B1904 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 .