DTC B1804: Short In Driver's Airbag

Diagnosis start condition:

When the ignition voltage is 10 - 16 V.

DTC detecting condition:

Short circuit malfunction between driver's airbag circuit and other circuit

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

NOTE:

Prior to starting work, prepare one AIRBAG RESISTOR (98299PA040).

CHECK POOR CONTACT OF CONNECTORS .
Check for poor contact of the connectors between the airbag control module and the driver's airbag module.

Is there poor contact?

Yes : Replace the airbag harness.

No : Go to 2.
CHECK DRIVER'S 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>NOTE>BATTERY
2. Remove the driver's airbag module.
3. Connect the connector (1N) in the test harness N to the connector (AB82).
4. Connect the airbag resistor to the connector (2N) of test harness N.
5. Connect the connector (1Q) in the test harness Q to connector (AB81).
6. Connect the airbag resistor to the connector (2Q) in the test harness Q.
7. Install the ground terminal to the battery sensor and turn the ignition switch to ON. Ref. to REPAIR CONTENTS>NOTE>BATTERY
8. Execute the inspection mode. Ref. to AIRBAG (DIAGNOSTICS)>INSPECTION MODE
9. Read the DTC of [Airbag] using the Subaru Select Monitor. Ref. to AIRBAG (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)
Is DTC B1804 displayed? (Current code)

Yes : Go to 3.

No : Replace the driver's airbag module. Ref. to AIRBAG SYSTEM>DRIVER'S AIRBAG MODULE
CHECK ROLL CONNECTOR (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 (AB83) from the passenger's airbag module.
3. Disconnect the connector (AB86) from the driver's knee airbag module.
4. Disconnect the connectors (AB41, AB42, AB43) from airbag control module.
5. Connect the connector (1BF) in the test harness BF to the connectors (AB41, AB42, AB43).
6. Disconnect the airbag resistor from the connector (2N) in test harness N and from the connector (2Q) in test harness Q.
7. Measure the resistance between connector (2Q) in the test harness Q and all connector terminals in the test harness BF.
  Connector & terminal
  
  (2Q) No. 1 - All terminals in test harness BF (except for (9BF) No. 1):
  
  (2Q) No. 2 - All terminals in test harness BF (except for (3BF) No. 1):
Is the resistance 1 MΩ or more?

Yes : Go to 4.

No : Replace the roll connector and faulty harness. (Replace the airbag main harness along with body harness. Or replace the airbag rear harness along with body harness.) Ref. to AIRBAG SYSTEM>ROLL CONNECTOR
CHECK AIRBAG MAIN HARNESS (DRIVER'S AIRBAG HARNESS) (SHORTED BETWEEN LINES) .
1. Disconnect the connector (AB46) from the roll connector.
2. Disconnect the test harness N from connector (AB82).
3. Disconnect the test harness Q from connector (AB81).
4. Measure the resistance between connectors (3BF) and (9BF) in the test harness BF and all connector terminals in the test harness BF.
  Connector & terminal
  
  (9BF) No. 1 - All terminals in test harness BF (except for (9BF) No. 1):
  
  (3BF) No. 1 - All terminals in test harness BF (except for (3BF) No. 1):
Is the resistance 1 MΩ or more?

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

No : Replace the faulty harness. (Replace the airbag main harness along with body harness. Or replace the airbag rear harness along with body harness.)