DTC B2905: Led Head Light Circuit LH

DTC detecting condition: 

Failure status of the LH headlight malfunction signal is detected for two seconds continuously.

Trouble symptom: 

LED headlight malfunction, LED headlight indicator illuminates.

Failure detection pattern: 

Detection by a single system (Primary Failure)

Warning light/indicator light: 

• Auto headlight beam leveler warning light -
• SRH warning light -
• ADB warning light -
• LED open circuit detection signal◦

Wiring diagram: 

• Headlight beam leveler system Ref. to WIRING SYSTEM>HEADLIGHT BEAM LEVELER SYSTEM>WIRING DIAGRAM .
• Headlight system Ref. to WIRING SYSTEM>HEADLIGHT SYSTEM>WIRING DIAGRAM .
• Clearance light: Bulb model

  Courtesy of SUBARU OF AMERICA, INC.

• Clearance light: LED model

Courtesy of SUBARU OF AMERICA, INC.

1. BASIC INSPECTION  .

   Before performing the diagnosis, perform basic inspection. Ref. to HEADLIGHT/FOGLIGHT (DIAGNOSTICS)>GENERAL DESCRIPTION>INSPECTION .

   NOTE:

   • Check the battery and its installation condition.
   • Check the related fuse.
   • Visually check that the related connectors are properly connected. Also, check the related ground terminal for looseness and corrosion.

   Is the check result OK?

   Yes  : GO TO  2.

   No  : Repair the defective part.

2. CHECK DTC  .
   1. Turn the ignition switch OFF → ON.
   2. Using the Subaru Select Monitor, perform the clear memory of [Headlight/Foglight]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY .
   3. Turn the ignition switch to OFF → ON.
   4. Turn the lighting switch to 2 (HEAD).
   5. Read the DTC of [Headlight/Foglight] using the Subaru Select Monitor. Ref. to HEADLIGHT/FOGLIGHT (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B2905 displayed? (Current code)

   Yes  : GO TO  3.

   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.

   After the repair, GO TO  9.

3. CHECK DATA MONITOR  .

   Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Headlight/Foglight]. Ref. to HEADLIGHT/FOGLIGHT (DIAGNOSTICS)>DATA MONITOR .

   • LED HEADLAMP (LH) error Signal

   Does the data display [OFF]?

   Yes  : Replace the auto headlight beam leveler control module. Ref. to LIGHTING SYSTEM>AUTO HEADLIGHT BEAM LEVELER CONTROL MODULE .

   After replacement, GO TO  9.

   No  : GO TO  4.

4. CHECK THE HEADLIGHT SYSTEM POWER SUPPLY CIRCUIT  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from the headlight assembly LH.
   3. Disconnect the connector from the headlight assembly RH.
   4. Turn the ignition switch to ON.
   5. Turn the lighting switch to 2 (HEAD).
   6. Using a tester, measure the voltage between headlight assembly LH connector and chassis ground.

      Connector & terminal 

      (B122) No. 1 (+) - Chassis ground (-):

   Is the voltage 8 - 16 V?

   Yes  : GO TO  5.

   No  : Repair the headlight system.

   After the repair, GO TO  9.

5. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Using a tester, measure the resistance between headlight assembly LH connector and chassis ground.

      Connector & terminal 

      Clearance light: Bulb model 

      (B122) No. 2 - Chassis ground:

      Clearance light: LED model

      (B122) No. 6 - Chassis ground:

   Is the resistance less than 10 Ω?

   Yes  : GO TO  6.

   No  : Repair or replace the open circuit of harness.

   After the repair, GO TO  9.

6. CHECK HEADLIGHT SYSTEM  .
   1. Connect the headlight assembly LH connector.
   2. Turn the ignition switch to ON.
   3. Turn the lighting switch to 2 (HEAD).

   Does the headlight come on at normal brightness?

   Yes  : GO TO  7.

   No  : Replace the headlight. Ref. to LIGHTING SYSTEM>HEADLIGHT ASSEMBLY .

   After replacement, GO TO  9.

7. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from the auto headlight beam leveler control module.
   3. Using a tester, measure the resistance between auto headlight beam leveler control module connector and headlight assembly LH connector.

      Connector & terminal 

      Clearance light: Bulb model 

      (B78) No. 11 - (B122) No. 4:

      Clearance light: LED model 

      (B78) No. 11 - (B122) No. 5:

   Is the resistance less than 10 Ω?

   Yes  : GO TO  8.

   No  : Repair or replace the open circuit of harness.

   After the repair, GO TO  9.

8. CHECK HARNESS (OPEN CIRCUIT)  .

   Using a tester, measure the resistance between the auto headlight beam leveler control module connector and chassis ground.

   Connector & terminal 

   (B78) No. 2 - Chassis ground:

   Is the resistance less than 10 Ω?

   Yes  : Replace the auto headlight beam leveler control module. Ref. to LIGHTING SYSTEM>AUTO HEADLIGHT BEAM LEVELER CONTROL MODULE .

   After replacement, GO TO  9.

   No  : Repair or replace the open circuit of harness.

   After the repair, GO TO  9.

9. CHECK REPAIR  .
   1. Perform the inspection mode corresponding to DTC. Ref. to HEADLIGHT/FOGLIGHT (DIAGNOSTICS)>INSPECTION MODE>PROCEDURE .
   2. Confirm that DTC or cancel code is not stored and the malfunction is eliminated.

   Is the check result OK?

   Yes  : Finish the diagnosis.

   No  : Perform the diagnosis according to the basic diagnostic procedure. Ref. to HEADLIGHT/FOGLIGHT (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .