DTC B1012: Battery Backup Power Supply

DTC detecting condition: 

Voltage failure caused by poor contact of battery power supply backup circuits

Trouble symptom: 

The keyless entry and map light do not illuminate.

Wiring diagram: 

Interior light system Ref. to WIRING SYSTEM>INTERIOR LIGHT SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Turn the ignition switch to ON.
   2. Read the DTC of [Body Control] using the Subaru Select Monitor. Ref. to BODY CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1012 displayed? (Current code)

   Yes:  Go to  2.

   No:  Go to  7.

2. CHECK DTC  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from body integrated unit.
   3. Connect the disconnected connectors.
   4. Wait approx. 2 minutes.
   5. Turn the ignition switch to ON.
   6. Read the DTC of [Body Control] using the Subaru Select Monitor. Ref. to BODY CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1012 displayed? (Current code)

   Yes:  Go to  3.

   No:  Go to  7.

3. CHECK FUSE  .
   1. Turn the ignition switch to OFF.
   2. Check the fuse. Ref. to WIRING SYSTEM>INTERIOR LIGHT SYSTEM>WIRING DIAGRAM .

   Is the check result OK?

   Yes:  Go to  4.

   No:  Replace the defective fuse.

4. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from F/B.
   3. Turn the ignition switch to ON.
   4. Using a tester, measure the voltage between the F/B connector and chassis ground.

      Connector & terminal 

      (i281) No. 27 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes:  Go to  5.

   No:  Repair the open circuit of the harness between F/B and fuse.

5. CHECK F/B UNIT  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the body integrated unit from F/B.
   3. Using a tester, check the continuity between F/B terminals.

      Connector & terminal 

      (i281) No. 27 - F/B No. 1:

   Is there continuity?

   Yes:  Go to  6.

   No:  Replace the F/B.

6. CHECK CONNECTOR  .

   Check poor contact of the connector between the body integrated unit and F/B.

   Is there poor contact of connector?

   Yes:  Repair the poor contact of connector.

   No:  Replace the body integrated unit. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT .

7. CHECK CONNECTOR  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the body integrated unit connector and the F/B connector.

   Is there poor contact of connector?

   Yes:  Repair or replace the poor contact of connector.

   No:  Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.