I use the fog lights very rarely so almost everytime i'm guessing which is for front halogen lights and which is back fog lights as the picture is almost the same... NOT AMY MORE! Here is why - I moded the backlight of that module:
The end result:
Colors from the photo don't match the actual colors but this the best my photo can do...
How it happens:
I cutted the backlighting guide to the two buttons for halogen lamps and back fog lamps. The groove that left was "stuffed" with something opaque, in my case with cable tape.Then I mounted the two LED's - white and orange.
The white one is "watching" sideways, because when it was downward it illuminated the button unevenly
If you hire to do such an exercise, make sure that everything is well insulated and there is no danger of shorting on the PCB. In my case, I'm flooded with hot silicone.
The power for these two LED's was taken from one of the three slots for the bulbs.
Oh, the bulbs are moded to LED, too, but that mod is old and well known so it's not interesting (I guess):
That's it
Good luck