DTC B1861: Open In Driver's Knee Airbag

Diagnosis start condition: 

When the ignition voltage is 10 - 16 V.

DTC detecting condition: 

• Airbag main harness circuit is open.
• Knee airbag module harness circuit is open.
• Knee 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.

1. CHECK POOR CONTACT OF CONNECTORS  .

   Check for poor contact of the connectors between the airbag control module and the knee airbag module.

   Is there poor contact?

   Yes  : Replace the airbag harness.

   No  : Go to  2.

2. CHECK KNEE 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. Disconnect the connector (AB66) from knee airbag module.
   3. Connect the connector (1N) in the test harness N to the connector (AB66).
   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>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 knee airbag module. Ref. to AIRBAG SYSTEM>KNEE AIRBAG MODULE>REMOVAL

   No  : Go to  3.

3. CHECK AIRBAG MAIN HARNESS (KNEE 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. Disconnect the airbag resistor from test harness N.
   3. Remove the instrument panel lower cover and column cover, and disconnect the connector (AB7) from (AB2).
   4. Remove the console front panel and disconnect the connector (AB9).
   5. Disconnect the connectors (AB6, AB17, AB18) from airbag control module.
   6. Connect the connector (1AG) in the test harness AG to the connectors (AB6, AB17, AB18).
   7. Measure the resistance between connector (3AG) in the test harness AG and connector (2N) in the test harness N.

      Connector & terminal 

      (3AG) No. 14 - (2N) No. 1:

      (3AG) No. 16 - (2N) No. 2:

   Is the resistance less than 10 Ω?

   Yes  : Go to  4.

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

4. 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 B1861 displayed? (Current malfunction)

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

   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.