DTC B2681: High Beam Assist Control Module

DTC detecting condition  :

• EEPROM malfunction.
• RAM malfunction.
• Ambient light sensor malfunction.

Trouble symptom  :

• High beam assist failure indicator illuminates, and failure message is displayed.
• High beam assist indicator does not illuminate.

Wiring diagram  :

• Rearview mirror system Ref. to WIRING SYSTEM>REARVIEW MIRROR SYSTEM>WIRING DIAGRAM .
• CAN communication system Ref. to WIRING SYSTEM>CAN COMMUNICATION 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 B2681 displayed? (Current code)

   Yes:  Go to  2.

   No:  Temporary access error occurs. Delete the DTC.

2. CHECK DATA MONITOR  .
   1. Turn the ignition switch to OFF.
   2. Turn the ignition switch to ON and wait for at least 15 seconds.
   3. Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Body Control]. Ref. to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR .
      • <HBA> ECU

   Is [Abnormal] displayed?

   Yes:  Replace the high beam assist module. Ref. to GLASS/WINDOWS/MIRRORS>REARVIEW MIRROR .

   No:  Go to  3.

3. CHECK POWER SUPPLY VOLTAGE  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the high beam assist module connector. Ref. to GLASS/WINDOWS/MIRRORS>REARVIEW MIRROR .
   3. Turn the ignition switch to ON.
   4. Using a tester, measure the voltage between terminals in the high beam assist module connector.

      Connector & terminal 

      (Rf44) No. 8 (+) - (Rf44) No. 2 (-):

   Is the voltage 10 V or more?

   Yes:  Replace the body integrated unit. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT .

   No:  Go to  4.

4. 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  5.

   No:  Replace the defective fuse. When the replaced fuse is blown, check the power supply circuit for short-circuited.

5. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Disconnect the high beam assist module connector. Ref. to GLASS/WINDOWS/MIRRORS>REARVIEW MIRROR .
   2. Using a tester, measure the resistance between the high beam assist module and chassis ground.

      Connector & terminal 

      (Rf44) No. 2 - Chassis ground:

   Is the resistance less than 10 Ω?

   Yes:  Replace the body integrated unit. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT .

   No:  Repair or replace the open circuit of harness.