Check Headlight System

Trouble symptom: 

Headlight does not illuminate, or headlight is weak.

1. CHECK HEADLIGHT AND TAIL LIGHT ILLUMINATION. 
   1. Turn the ignition switch to ON.
   2. Set the lighting switch to the switch 1 (TAIL) and switch 2 (HEAD).
   3. Turn the dimmer & passing switch to the switch UP position.

   Do the headlight (low beam and high beam) and tail light come on?

   Yes:  The headlight system is normal.

   No:  Go to  2.

2. CHECK CURRENT DATA. 

   Display the data of [LED HEADLAMP (RH) error Signal] and [LED HEADLAMP (LH) error Signal] using Subaru Select Monitor. Refer to HEADLIGHT/FOGLIGHT (DIAGNOSTICS)>DATA MONITOR .

   Is [Turn_ON] displayed?

   Yes:  Go to  3.

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

3. CHECK CONNECTOR CONNECTION. 

   Check that the headlight connector is connected.

   Is the connector connected?

   Yes:  Go to  4.

   No:  Connect the connector.

   When it does not illuminate even though the switch is turned to ON: Go to  4.

4. CHECK HARNESS. 
   1. Disconnect the headlight connector.
   2. Turn the ignition switch to ON.
   3. Measure the voltage between the headlight connector and chassis ground.

      Connector & terminal 

      RH side 

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

      (B487) No. 2 (+) - Chassis ground (-):

      LH side 

      (B477) No. 1 (+) - Chassis ground (-):

      (B477) No. 2 (+) - Chassis ground (-):

   Is the voltage 10 - 13.5 V?

   Yes:  Go to  5.

   No:  Go to  6.

5. CHECK HEADLIGHT. 

   Apply battery voltage between headlight unit connector terminals.

   Terminals 

   Low beam 

   No. 1 (+) - No. 3 (-):

   High beam 

   No. 2 (+) - No. 3 (-):

   Does the headlight (low beam and high beam) come on at normal brightness?

   Yes:  Go to  6.

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

   Perform inspection for the malfunction signal line if the [LED HEADLAMP (RH) error Signal] and [LED HEADLAMP (LH) error Signal] do not illuminate in step 2). If short circuit to power supply occurs, repair or replace the harness.

6. CHECK FUSE AND RELAY. 
   1. Turn the ignition switch to OFF.
   2. Check the M/B fuse No. 4, M/B fuse No. 3 and H/L LO relay. Refer to LIGHTING SYSTEM>RELAY AND FUSE>INSPECTION .

   Is the check result OK?

   Yes:  Go to  7.

   No:  Replace the defective fuse or relay.

7. CHECK CURRENT DATA. 
   1. Display the following items using Subaru Select Monitor. Refer to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR .
      • [key-lock warning SW]: (model without keyless access with push button start)
      • [ACC Input]: (model with keyless access with push button start)
   2. Turn the ignition switch to ON.

   Does the display switch between [OFF] → [ON] after operating the ignition switch?

   Yes:  Go to  8.

   No:  Replace the body integrated unit. Refer to SECURITY AND LOCKS>BODY INTEGRATED UNIT .

8. CHECK HARNESS. 
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector of body integrated unit.
   3. Measure the voltage between the body integrated unit connector and chassis ground.

      Connector & terminal 

      (B280) No. 3 (+) - Chassis ground (-):

      (B287) No. 3 (+) - Chassis ground (-):

   Is the voltage 8.5 - 16.5 V?

   Yes:  Go to  9.

   No:  Repair or replace the harness.

9. CHECK CURRENT DATA. 
   1. Turn the ignition switch to ON.
   2. Display the data of [Lighting I Switch Input], [Lighting II Switch Input] and [Dimmer Hi Switch Input] using Subaru Select Monitor. Refer to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR .
   • Do the displays of [Lighting I Switch Input] and [Lighting II Switch Input] switch between [OFF] ←→ [ON] when the lighting switch is moved from OFF position to switch 1 (TAIL) and switch 2 (HEAD) positions?
   • Does the display of [Dimmer Hi Switch Input] switch between [OFF] ←→ [ON] when the dimmer & passing switch is moved to the switch UP position?

   Yes:  Go to  13.

   No:  Go to  10.

10. CHECK COMBINATION SWITCH (LIGHT). 
    1. Turn the ignition switch to OFF.
    2. Check the combination switch (light). Refer to LIGHTING SYSTEM>COMBINATION SWITCH (LIGHT)>INSPECTION .

    Is the combination switch (light) normal?

    Yes:  Go to  11.

    No:  Replace the combination switch (light). Refer to LIGHTING SYSTEM>COMBINATION SWITCH (LIGHT) .

11. CHECK HARNESS. 
    1. Disconnect the connector of body integrated unit.
    2. Check the harness between body integrated unit and combination switch (light).

       Connector & terminal 

       (i171) No. 35 - (i73) No. 18:

       (i171) No. 19 - (i73) No. 20:

       (i81) No. 28 - (i73) No. 20:

       (i171) No. 26 - (i73) No. 11:

       (i171) No. 36 - (i73) No. 17:

    Is harness normal?

    Yes:  Go to  12.

    No:  Repair or replace the harness.

12. CHECK HARNESS. 

    Check the harness between the combination switch (light) connector and the chassis ground.

    Connector & terminal 

    (i73) No. 12 - Chassis ground:

    Is the resistance less than 10 Ω?

    Yes:  Go to  13.

    No:  Repair or replace the harness.

13. CHECK CURRENT DATA. 
    1. Turn the ignition switch to ON.
    2. Display the data of [Lighting I Lamp Output], [Lighting II Lamp Output] and [Lighting Hi Lamp Output] using Subaru Select Monitor. Refer to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR .
    • Do the displays of [Lighting I Lamp Output] and [Lighting II Lamp Output] switch between [OFF] ←→ [ON] when the lighting switch is moved from OFF position to switch 1 (TAIL) and switch 2 (HEAD) positions?
    • Does the display of [Lighting Hi Lamp Output] switch between [OFF] ←→ [ON] when the dimmer & passing switch is moved to the switch UP position?

    Yes:  Check the body integrated unit and replace it if defective.

    • Inspection: Refer to BODY CONTROL (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
    • Replacement: Refer to SECURITY AND LOCKS>BODY INTEGRATED UNIT .

    No:  Go to  14.

14. CHECK HARNESS. 
    1. Turn the ignition switch to OFF.
    2. Disconnect the connectors of body integrated unit and each light.
    3. Check the harness between body integrated unit and each light.

       Connector & terminal 

       Headlight 

       (B280) No. 9 - (B487) No. 2:

       (B287) No. 7 - (B477) No. 2:

       Parking light and front side marker (model without SRH)

       (B280) No. 10 - (B620) No. 2:

       (B280) No. 10 - (B621) No. 2:

       Parking light and front side marker (model with SRH)

       (B280) No. 10 - (B487) No. 8:

       (B280) No. 10 - (B477) No. 8:

       Rear combination light

       (B280) No. 10 - (R26) No. 1:

       (B280) No. 10 - (R28) No. 1:

       Rear finisher light

       (B280) No. 10 - (D87) No. 4:

       (B280) No. 10 - (D91) No. 4:

       License plate light

       (B280) No. 10 - (D44) No. 1:

       (B280) No. 10 - (D137) No. 1:

       Relay

       H/L LO relay No. 4 - (B287) No. 6:

       H/L LO relay No. 4 - (i171) No. 23:

       H/L LO relay No. 2 - (B281) No. 20:

       H/L LO relay No. 2 - (i171) No. 18:

    Is harness normal?

    Yes:  Go to  15.

    No:  Repair or replace the harness.

15. CHECK HARNESS. 

    Check the harness between each light connector and the chassis ground.

    Connector & terminal 

    Headlight

    (B487) No. 3 - Chassis ground:

    (B477) No. 3 - Chassis ground:

    Parking light and front side marker (model without SRH)

    (B620) No. 6 - Chassis ground:

    (B621) No. 6 - Chassis ground:

    Parking light and front side marker (model with SRH)

    (B487) No. 3 - Chassis ground:

    (B477) No. 3 - Chassis ground:

    Rear combination light

    (R26) No. 4 - Chassis ground:

    (R28) No. 4 - Chassis ground:

    Rear finisher light

    (D87) No. 3 - Chassis ground:

    (D91) No. 3 - Chassis ground:

    License plate light

    (D44) No. 2 - Chassis ground:

    (D137) No. 2 - Chassis ground:

    Is harness normal?

    Yes:  Check the body integrated unit and replace it if defective.

    • Inspection: Refer to BODY CONTROL (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
    • Replacement: Refer to SECURITY AND LOCKS>BODY INTEGRATED UNIT .

    No:  Repair or replace the harness.