Auto Headlight System Check

NOTE: Check the headlight system before checking the auto headlight system.

Halogen headlight: Ref. to LIGHTING SYSTEM>Headlight System>INSPECTION>CHECK HALOGEN HEADLIGHT SYSTEM .
LED headlight: Ref. to LIGHTING SYSTEM>Headlight System>INSPECTION>CHECK LED HEADLIGHT SYSTEM .

CHECK HEADLIGHT AND TAIL LIGHT ILLUMINATION.
1. Turn the ignition switch to ON.
2. Make the light control sensor vicinity dark.
3. Set the lighting switch to AUTO position.
4. Make the light control sensor vicinity bright.
5. Turn the lighting switch to the OFF position and turn to the AUTO position again.
Do the parking light, headlight and tail light illuminate?

Yes: The auto headlight system is normal.

No: Go to 2
CHECK CURRENT DATA.
1. Using the Subaru Select Monitor, display the data of «Illumination Sensor Output».
2. Measure the voltage when the area around the light control sensor, which was dark, becomes bright.
NOTE: For detailed operation procedures, refer to "Application help".

Illumination sensor output

Dark condition: Approx. 0.6 V or less

Bright condition: Approx. 3 V or more

Is the voltage output according to the brightness?

Yes: Go to 5

No: Go to 3
CHECK LIGHT CONTROL SENSOR.
Check the light control sensor. Ref. to LIGHTING SYSTEM>Light Control Sensor>INSPECTION .

Is the light control sensor normal?

Yes: Go to 4

No: Replace the light control sensor.
CHECK HARNESS.
1. Disconnect the connectors from body integrated unit and light control sensor.
2. Check the harness between body integrated unit and light control sensor.
Connector & terminal

(i171) No. 8 - (i89) No. 1:

(i171) No. 28 - (i89) No. 2:

(i171) No. 27 - (i89) No. 3:

Is harness normal?

Yes: Check the body integrated unit and replace it if defective.
- Inspection: Ref. to BODY CONTROL SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
- Replacement: Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .
No: Repair or replace the harness.
CHECK CURRENT DATA.
Using the Subaru Select Monitor, display the data of «Lighting AUTO input».

Does the display switch between «OFF»↔«ON» when the lighting switch is moved from OFF position to the AUTO position?

Yes: Check the body integrated unit and replace it if defective.
- Inspection: Ref. to BODY CONTROL SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
- Replacement: Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .
No: Go to 6
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 7

No: Replace the combination switch (light). Ref. to LIGHTING SYSTEM>COMBINATION SWITCH (LIGHT) .
CHECK HARNESS.
1. Disconnect the connectors of body integrated unit and combination switch (light).
2. Check the harness between body integrated unit and combination switch (light).
Is harness normal?

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