DTC B1678: Lost Communication With Satellite SAFING Sensor

Diagnosis start condition:

When the ignition voltage is 10 - 16 V.

DTC detecting condition:

Open or short circuit in harness of Side impact sensor (under the rear center seat)
Side impact sensor (under the rear center seat) is faulty.
Airbag control module is faulty.

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 (AB41, AB60) between the airbag control module and Side impact sensor (under the rear center seat).

Is there poor contact?

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

No: GO TO 2.
CHECK AIRBAG REAR HARNESS (BETWEEN AIRBAG CONTROL MODULE AND) .
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 (AB100) from rear seat belt pretensioner LH.
5. Disconnect the connector (AB92) from curtain airbag module LH.
6. Disconnect the connector (AB88) from side airbag module LH.
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. Disconnect the connector (AB60) from Side impact sensor (under the rear center seat).
10. Connect the connector (1BI) in the test harness BI to the connector (AB60).
11. Measure the resistance between the connector (6BF) in the test harness BF and the connector (2BI) in the test harness BI.
  Connector & terminal
  
  (6BF) No. 9 - (2BI) No. 1:
  
  (6BF) No. 4 - (2BI) No. 2:
Is the resistance less than 10 Ω?

Yes: GO TO 3.

No: Replace the airbag rear harness along with body harness.
CHECK AIRBAG REAR HARNESS (BETWEEN AIRBAG CONTROL MODULE AND Side impact sensor (under the rear center seat)) .
Measure the resistance between connector (6BF) in the test harness BF and chassis ground, and the resistance between connector (6BF) in the test harness BF.

Connector & terminal

(6BF) No. 9 - Chassis ground:

(6BF) No. 4 - Chassis ground:

(6BF) No. 9 - (6BF) No. 4:

Is the resistance 1 MΩ or more?

Yes: GO TO 4.

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 connectors.
3. Using the Subaru Select Monitor, perform the clear memory of [Airbag]. Ref. to COMMON (DIAGNOSTICS)>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 B1678 or B1679 displayed? (Current code)

Yes: Replace Side impact sensor (under the rear center seat). Ref. to AIRBAG SYSTEM>IMPACT SENSOR>REMOVAL>SIDE IMPACT SENSOR (UNDER THE REAR CENTER SEAT) . Replace the airbag control module if not operating normally even after replacing the sensor. Ref. to AIRBAG SYSTEM>AIRBAG CONTROL MODULE>REMOVAL .

No: Finish the diagnosis.