Auto Headlight System Check

Wiring diagram: 

Headlight system Ref. to WIRING SYSTEM>HEADLIGHT SYSTEM>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

1. 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 by way of step 3 and go off by step 5?

   Yes  : The auto headlight system is normal.

   No  : Go to  2.

2. CHECK BODY INTEGRATED UNIT SETTING  .

   Using Subaru Select Monitor, display data of [Illumination Sensor Setting] in [Customize] of [Body Control]. Ref. to BODY CONTROL (DIAGNOSTICS)>CUSTOMIZE

   Is the setting in the [Support]?

   Yes  : Go to  3.

   No  : Turn the setting to [Support].

3. CHECK CURRENT DATA  .
   1. Using Subaru Select Monitor, display data of [Illumination Sensor Output] in [Data Monitor] of [Body Control]. Ref. to COMMON (DIAGNOSTICS)>DATA MONITOR
   2. Measure the voltage when the area around the light control sensor, which was dark, becomes bright.

      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  6.

   No  : Go to  4.

4. 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  5.

   No  : Replace the light control sensor. Ref. to LIGHTING SYSTEM>LIGHT CONTROL SENSOR 

5. 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 

      (i82) No. 8 - (i159) No. 1:

      (i82) No. 28 - (i159) No. 2:

      (i82) No. 34 - (i159) No. 3:

   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 BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT

   No  : Repair or replace the defective part.

6. CHECK CURRENT DATA  .
   1. Set the lighting switch to AUTO position.
   2. Using the Subaru Select Monitor, display the following items in the [Data monitor] of [Body Control]. Ref. to COMMON (DIAGNOSTICS)>DATA MONITOR
      • Other than for C0
        • [Writing AUTO SW input]
      • For C0
        • [Lighting I Switch Input]
        • [Lighting II Switch Input]
        • [Lighting OFF Switch Input]
   • Is [Writing AUTO SW input] set to [ON]? (Except for C0)
   • Are [Lighting I Switch Input], [Lighting II Switch Input] and [Lighting OFF Switch Input] set to [OFF]? (For C0)

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

   • Inspection: Ref. to BODY CONTROL (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE
   • Replacement: Ref. to BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT

   No  : Go to  7.

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) 

8. 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).

      Connector & terminal 

      Other than for C0 

      (i82) No. 35 - (i131) No. 18:

      (i83) No. 20 - (i131) No. 19:

      (i83) No. 28 - (i131) No. 20:

      For C0 

      (i82) No. 35 - (i131) No. 19:

      (i83) No. 20 - (i131) No. 18:

      (i83) No. 28 - (i131) No. 20:

   Is harness normal?

   Yes  : Go to  9.

   No  : Repair or replace the defective part.

9. CHECK HARNESS  .

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

   Connector & terminal 

   (i131) No. 13 - Chassis ground:

   Is the resistance less than 10 Ω?

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

   • Inspection: Ref. to BODY CONTROL (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE
   • Replacement: Ref. to BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT

   No  : Repair or replace the defective part.