Check Fog Light System

Trouble symptom: 

Fog light does not illuminate.

1. CHECK DTC  .
   1. Turn the ignition switch to ON.
   2. Turn the lighting switch to the switch 2 (HEAD) position.
   3. Turn the front fog light switch of the lighting switch to ON.
   4. Read the DTC of [Front Relay Control Module] using the Subaru Select Monitor. Ref. to FRONT RELAY CONTROL MODULE (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

      Are any DTCs displayed?

      Yes  : Perform the diagnosis according to the displayed DTC. Ref. to FRONT RELAY CONTROL MODULE (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .

      No  : Go to  2 .

2. CHECK POWER SUPPLY  .

   Display the data of [Body control] and [Front Relay Control Module] using Subaru Select Monitor.

   • Body control

     Display the data of [BATT voltage (control)], [BATT voltage (BACKUP)] and [IGNITION POWER]. Ref. to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR .

   • Front relay control module

     Display the data of [BATT Voltage (Control)], [BATT Voltage (BACKUP)] and [IGN Voltage]. Ref. to FRONT RELAY CONTROL MODULE (DIAGNOSTICS)>DATA MONITOR .

   Is the voltage 9 - 16 V?

   Yes  : Go to  3 .

   No  : 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 .

     Check the front relay control module and replace it if defective.

   • Inspection: Ref. to FRONT RELAY CONTROL MODULE (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
   • Replacement: Ref. to BODY CONTROL/COMMUNICATION SYSTEM>FRONT RELAY CONTROL MODULE .
3. PERFORM ACTIVE TEST  .

   Using the Subaru Select Monitor, select [F Fog Light Output] of [Active Test] to turn on the front fog light. Ref. to FRONT RELAY CONTROL MODULE (DIAGNOSTICS)>ACTIVE TEST .

   Does it illuminate?

   Yes  : Go to  4 .

   No  : Check the harness of the relay and output circuit. If there are no problems, replace the front relay control module. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>FRONT RELAY CONTROL MODULE .

4. CHECK CURRENT DATA  .
   1. Turn the ignition switch to ON.
   2. Display the [Front Fog Light SW input] data using Subaru Select Monitor. Ref. to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR .

      Does the display change from [OFF] ←→ [ON] when the front fog light switch of the lighting switch is operated?

      Yes  : Go to  5 .

      No  : Check the harnesses of the combination switch, connector and input circuit. If there are no problems, replace the body integrated unit. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT .

5. CHECK CURRENT DATA  .
   1. Turn the ignition switch to ON.
   2. Display the [F Fog Light Request] data using Subaru Select Monitor. Ref. to FRONT RELAY CONTROL MODULE (DIAGNOSTICS)>DATA MONITOR .

      Does the display change from [OFF] ←→ [ON] when the front fog light switch of the lighting switch is operated?

      Yes  : Replace the front relay control module. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>FRONT RELAY CONTROL MODULE .

      No  : Replace the body integrated unit. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT .