DTC B1801: Open In Driver's Airbag

Diagnosis start condition:

When the ignition voltage is 10 - 16 V.

DTC detecting condition:

Airbag main harness circuit is open.
Airbag module harness (driver's side) circuit is open.
Roll connector is open.
Driver's airbag module 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.

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

NOTE: Prior to starting work, prepare two AIRBAG RESISTORS (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>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. Remove the driver's airbag module.
3. Connect the connector (1N) in the test harness N to the connector (AB38).
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 (AB37).
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>REPAIR CONTENTS>NOTE>BATTERY .
  NOTE: For the hybrid model, connect the battery ground terminal and turn the ignition switch to ON.
Does the airbag warning light illuminate for six seconds and go off?

Yes : Replace the driver's airbag module. Ref. to AIRBAG SYSTEM>DRIVER'S AIRBAG MODULE .

No : Go to 3.
CHECK ROLL CONNECTOR AND AIRBAG MAIN HARNESS (DRIVER'S AIRBAG HARNESS) .
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. Remove the console front panel and disconnect the connector (AB9).
3. Disconnect the driver's knee airbag module connector (AB66).
4. Disconnect the airbag resistor from the connector (2N) in test harness N.
5. Disconnect the airbag resistor from the connector (2Q) of test harness Q.
6. Disconnect the connectors (AB6, AB17, AB18) from airbag control module.
7. Measure the resistance between connector (2Q) terminals in test harness Q.
  Connector & terminal
  
  (2Q) No. 1 - (2Q) No. 2:
Is the resistance less than 10 Ω?

Yes : Go to 5.

No : Go to 4.
CHECK ROLL CONNECTOR .
1. Remove the instrument panel lower cover and column cover, and disconnect the connector (AB7) from (AB2).
2. Measure the resistance between connector (2Q) terminals in test harness Q.
  Connector & terminal
  
  (2Q) No. 1 - (2Q) No. 2:
Is the resistance less than 10 Ω?

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

No : Replace the roll connector. Ref. to AIRBAG SYSTEM>ROLL CONNECTOR .
CHECK AIRBAG CONTROL MODULE .
1. Connect all connectors.
2. 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.
3. Using the Subaru Select Monitor, perform the clear memory of [Airbag]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
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 B1801 displayed? (Current malfunction)

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

No : Go to 6.
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.