Check Headlight System

Trouble symptom:

Headlight does not illuminate, or headlight is weak.

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).
  Do the headlight and tail light illuminate?
  
  Yes: The headlight system is normal.
  
  No: Go to 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 .
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 .
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 .
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. 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.
CHECK CURRENT DATA .
1. Turn the ignition switch to ON.
2. Display the data of [Lighting I Switch Input] and [Lighting II Switch Input] using Subaru Select Monitor. Ref. to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR .
Does the display switch between [OFF] ←→ [ON] when the lighting switch is moved from OFF position to switch 1 (TAIL) and switch 2 (HEAD) positions?

Yes: Go to 9 .

No: Go to 7 .
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 8 .

No: Replace the combination switch (light). Ref. to LIGHTING SYSTEM>COMBINATION SWITCH (LIGHT) .
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:
Is harness normal?

Yes: Check the body integrated unit and replace it if defective.
- Inspection: Ref. to BODY CONTROL (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
- Replacement: Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .
No: Repair or replace the harness.
CHECK CURRENT DATA .
1. Turn the ignition switch to ON.
2. Display the data of [Lighting I Lamp Output] and [Lighting II Lamp Output] using Subaru Select Monitor. Ref. to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR .
Does the display switch between [OFF] ←→ [ON] when the lighting switch is moved from OFF position to switch 1 (TAIL) and switch 2 (HEAD) positions?

Yes: Check the body integrated unit and replace it if defective.
- Inspection: Ref. to BODY CONTROL (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
- Replacement: Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .
No: Go to 10 .
CHECK HARNESS .
1. Turn the ignition switch to OFF.
2. Disconnect the body integrated unit connector and the headlight and tail light connectors.
3. Check the harness between body integrated unit and headlight and between body integrated unit and tail light.
  Connector & terminal
  
  Headlight RH
  
  (B280) No. 9 - (B487) No. 2:
  
  Headlight LH
  
  (B287) No. 7 - (B477) No. 2:
  
  Rear combination light RH
  
  (B280) No. 10 - (R266) No. 4:
  
  Rear combination light LH
  
  (B280) No. 10 - (R208) No. 4:
  
  Rear finisher light RH
  
  (B280) No. 10 - (D87) No. 4:
  
  Rear finisher light LH
  
  (B280) No. 10 - (D91) No. 4:
Is harness normal?

Yes: Check the body integrated unit and replace it if defective.
- Inspection: Ref. to BODY CONTROL(DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
- Replacement: Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .
No: Repair or replace the harness.