DTC B2904: Led Headlight Circuit RH

DTC detecting condition: 

LED headlight (RH) malfunction signal line error is detected for 2 seconds or more.

Trouble symptom: 

LED headlight malfunction, LED headlight indicator illuminates.

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 .

Courtesy of SUBARU OF AMERICA, INC.

1. 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 (DIAG)>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 B2904 displayed? (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 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 (RH) error Signal

   Does the data indicate [Light off]?

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

   No:  Go to  3.

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

   Connector & terminal 

   (B487) No. 1 (+) - Chassis ground (-):

   Is the voltage 10 - 13 V?

   Yes:  Go to  4.

   No:  Repair the headlight system.

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

   Connector & terminal 

   (B487) No. 3 - Chassis ground:

   Is the resistance less than 10 Ω?

   Yes:  Go to  5.

   No:  Repair or replace the open circuit of harness.

5. CHECK HEADLIGHT SYSTEM. 
   1. Connect the headlight assembly RH connector.
   2. Turn the ignition switch to OFF → ON.
   3. Turn the lighting switch to 2 (HEAD).

   Does the headlight come on at normal brightness?

   Yes:  Go to  6.

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

6. CHECK HARNESS (OPEN CIRCUIT). 
   1. Turn the ignition switch to OFF.
   2. Disconnect the auto headlight beam leveler Control Module connector.
   3. Using a tester, measure the resistance between auto headlight beam leveler Control Module connector and headlight assembly RH connector.

   Connector & terminal 

   (B616) No. 12 - (B487) No. 5:

   Is the resistance less than 10 Ω?

   Yes:  Go to  7.

   No:  Repair or replace the open circuit of harness.

7. CHECK HARNESS (OPEN CIRCUIT). 

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

   Connector & terminal 

   (B616) 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 .

   No:  Repair or replace the open circuit of harness.