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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. Ref. to HEADLIGHT/FOGLIGHT (DIAGNOSTICS)>DATA MONITOR .

    Is [Turn_ON] displayed?

    Yes:  Go to  3.

    No:  Replace the headlight assembly. Ref. 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. 1, 2 (+) - No. 3 (-):

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

    Yes:  Go to  6.

    No:  Replace the headlight. Ref. 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. Ref. 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. Ref. 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. Ref. 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. Ref. 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 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). Ref. to LIGHTING SYSTEM>COMBINATION SWITCH (LIGHT)>INSPECTION .

    Is the combination switch (light) normal?

    Yes:  Go to  11.

    No:  Replace the combination switch (light). Ref. 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: (except for C5)

      (i171) No. 35 - (i73) No. 19: (for C5)

      (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. Ref. 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 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:  Go to  14.

    No:  Check the body integrated unit and replace it if defective.

  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 

      (B280) No. 10 - (B487) No. 6:

      (B280) No. 10 - (B477) No. 6:

      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 

    (B487) No. 8 - Chassis ground:

    (B477) No. 8 - 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.

    No:  Repair or replace the harness.

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