Front Fog Light System: Inspection: Trouble Symptom

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

Fog light does not illuminate.

NOTE:

Operate the appropriate switch according to the inspection condition.

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 DTCs of the following items using the Subaru Select Monitor. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)
  - [Body Control]
  - [Front Relay Control Module]
Is DTC displayed?

Yes : Perform the diagnosis for the displayed DTCs.
- [Body Control]: Ref. to BODY CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST
- [Front Relay Control Module]: Ref. to FRONT RELAY CONTROL MODULE (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST
No : Go to 2.
CHECK POWER SUPPLY .
Display data of the following items using Subaru Select Monitor. Ref. to COMMON (DIAGNOSTICS)>DATA MONITOR
- [Body Control]
  - [BATT voltage (control)]
  - [BATT voltage (BACKUP)]
  - [IGN voltage]
- [Front Relay Control Module]
  - [BATT Voltage (Control)]
  - [BATT Voltage (BACKUP)]
  - [IGN Voltage]
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
PERFORM ACTIVE TEST .
Using the Subaru Select Monitor, select [F Fog Light Output] in [Active Test] of [Front Relay Control Module] 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
CHECK CURRENT DATA .
1. Turn the ignition switch to ON.
2. Using Subaru Select Monitor, display [Front Fog Light SW input] in [Data monitor] of [Body Control]. Ref. to COMMON (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
CHECK CURRENT DATA .
1. Turn the ignition switch to ON.
2. Using Subaru Select Monitor, display [F Fog Light Request] in [Data monitor] of [Front Relay Control Module]. Ref. to COMMON (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