DTC B1A01: Front Relay Control Module Battery (Control) Power Supply

DTC detecting condition: 

When the ignition is ON or during CAN communication, battery voltage exceeded the range of 9 - 16 V for 40 seconds or more.

Trouble symptom: 

-

Wiring diagram: 

Headlight system Ref. to WIRING SYSTEM>HEADLIGHT SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Turn the ignition switch to ON.
   2. Read the DTC of [Front Relay Control Module] using the Subaru Select Monitor. Ref. to FRONT RELAY CONTROL MODULE (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1A01 displayed? (Current code)

   Yes:  Go to  2.

   No:  Go to  5.

2. CHECK DTC  .
   1. Turn the ignition switch to OFF.
   2. Disconnect Front relay control module connectors (B68, B69) and reconnect them.
   3. Turn the ignition switch to ON.
   4. Wait approx. 1 minute.
   5. Read the DTC of [Front Relay Control Module] using the Subaru Select Monitor. Ref. to FRONT RELAY CONTROL MODULE (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1A01 displayed? (Current code)

   Yes:  Go to  3.

   No:  Go to  5.

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

   Is the check result OK?

   Yes:  Go to  4.

   No:  Replace the defective fuse.

4. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Disconnect Front relay control module connector (B68).
   2. Using the tester, measure the voltage between terminals.

      Connector & terminal 

      (B68) No. 5 (+) - Chassis ground (-):

   Is the voltage 8.5 - 16.5 V?

   Yes:  Go to  5.

   No:  Repair the harness between Front relay control module and fuse.

5. CHECK CONNECTOR  .
   1. Turn the ignition switch to OFF.
   2. Disconnect Front relay control module connectors (B68, B69).

   Is there poor contact of connector?

   Yes:  When moved from step 1 or step 2: Repair or replace the poor contact of connector.

   When moved from step 4: Repair or replace the connector, and check DTC. When DTC B1A01 is displayed, replace the Front relay control module. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>FRONT RELAY CONTROL MODULE .

   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.