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: 

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

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .

   Read the DTC of body integrated unit using Subaru Select Monitor. Ref. BODY CONTROL SYSTEM (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC) .

   Is DTC B2681 a current malfunction?

   Yes: Go to  2.

   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.
2. CHECK CURRENT DATA  .
   1. Turn the ignition switch to OFF.
   2. Turn the ignition switch to ON and wait for at least 15 seconds.
   3. Check the current data «<HBA> ECU» of body integrated unit using Subaru Select Monitor. Ref. BODY CONTROL SYSTEM (DIAGNOSTICS)>Read Current Data .

   Is «FAIL» 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. Start the engine.
   4. Use a tester to measure the voltage between the terminals.

      Connector & terminal

      (R165) No. 1 (+) - (R165) No. 2 (-):

   Is the voltage 10 V or more?

   Yes: Go to  7.

   No: Go to  4.

4. CHECK FUSE  .
   1. Turn the ignition switch to OFF.
   2. Check the fuse.

   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 the tester, measure the resistance between terminals.

      Connector & terminal

      (R165) No. 2 - Chassis ground:

   Is the resistance less than 10 Ω?

   Yes: Go to  6.

   No: Repair or replace the open circuit of harness.

6. CHECK CURRENT DATA  .
   1. Connect the disconnected connectors.
   2. Turn the ignition switch to ON and wait for at least 15 seconds.
   3. Check the current data «<HBA>High Beam Assist Camera» of body integrated unit using Subaru Select Monitor. Ref. BODY CONTROL SYSTEM (DIAGNOSTICS)>Read Current Data .

   Is «FAIL» displayed?

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

   No: Go to  7.

7. CHECK DTC  .

   Read the DTC of body integrated unit using Subaru Select Monitor. Ref. BODY CONTROL SYSTEM (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC) .

   Is DTC B2681 a current malfunction?

   Yes: Replace the body integrated unit. Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .

   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.