Auto Headlight System Check

WARNING: This page is about a different car, the 2016 Subaru Impreza and 2016 Subaru Crosstrek. However, it is still accessible from the selected car via links, so may be relevant.

DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK HEADLIGHT ILLUMINATION. Set the lighting switch to the switch 1 (TAIL) and switch 2 (HEAD).	Do the tail and headlight illuminate?	Go to step 2.	Check the combination switch (light) and headlight bulb.
2 CHECK CURRENT DATA. Using the Subaru Select Monitor, display the data of «Lighting AUTO input». NOTE: For detailed operation procedures, refer to "Application help".	Does the display switch between OFF ←→ ON when the lighting switch is moved to AUTO position?	Go to step 3.	Go to step 8.
3 CHECK CURRENT DATA. Using the Subaru Select Monitor, display the data of «Illumination Sensor Output». 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. 3.0 V or more	Is the voltage output according to the brightness?	Check and replace the body integrated unit. Inspection: < Ref. to BASIC DIAGNOSTIC PROCEDURE . > Replacement: < Ref. to BODY INTEGRATED UNIT . >	Go to step 4.
4 CHECK HARNESS. Disconnect the connectors from body integrated unit and light control sensor. Check the harness between body integrated unit and light control sensor. Connector & terminal (B280) No. 19 - (i226) No. 2: (B280) No. 29 - (i226) No. 1: (B281) No. 1 - (i226) No. 3:	Is harness normal?	Go to step 5.	Repair or replace the harness.
5 CHECK HARNESS. Connect the connector of body integrated unit. Turn the ignition switch to ON. Measure the voltage between light control sensor connector and chassis ground. Connector & terminal (i226) No. 3 (+) - Chassis ground (-):	Is the voltage 4.5 - 5.5 V?	Go to step 6.	Replace the body integrated unit. < Ref. to BODY INTEGRATED UNIT . >
6 CHECK BODY INTEGRATED UNIT. Measure the resistance between the body integrated unit and chassis ground. Connector & terminal (B280) No. 29 - Chassis ground:	Is the resistance less than 10 Ω?	Go to step 7.	Replace the body integrated unit. < Ref. to BODY INTEGRATED UNIT . >
7 CHECK LIGHT CONTROL SENSOR. Connect the light control sensor connector. Check the light control sensor. < Ref. to INSPECTION , Light Control Sensor. >	Is the light control sensor normal?	Go to step 8.	Replace the light control sensor.
8 CHECK COMBINATION SWITCH (LIGHT). Check the combination switch (light). < Ref. to INSPECTION , Combination Switch (Light). >	Is the combination switch (light) normal?	Go to step 9.	Replace the combination switch (light).
9 CHECK HARNESS. Disconnect the connectors of body integrated unit and combination switch (light). Check the harness between body integrated unit and combination switch (light). Connector & terminal (B71) No. 19 - (B281) No. 16:	Is harness normal?	Check and replace the body integrated unit. Inspection: < Ref. to BASIC DIAGNOSTIC PROCEDURE . > Replacement: < Ref. to BODY INTEGRATED UNIT . >	Repair or replace the harness.