In England you do not use your front or rear fog lights when it is not foggy – if you accidentally turn them on you will soon know it, as you annoy many other drivers who in turn will flash full beam headlights at you to remind you to correct your bad lighting.
Front fog lights should be designed very low to the ground and are only of benefit in VERY foggy conditions where the headlights are just creating glare, being reflected right back at you so that you see worse with them on than off – this is why on the MINI you can have front fog lights on with side lights; that is the best way to drive in really thick fog.
Rear fog lights are as bright as brake lights, and should be turned on in foggy conditions if there is a chance that an approaching driver behind you cannot see your less bright side lights. The brighter rear fog lights enable the approaching driver to see you earlier – once the car behind you is closer, you should out of courtesy switch off your rear fog lights to prevent dazzle (and to make it easier to recognize when you are braking).
In USA it appears that there are completely different rules. Front fog lights are often so high (especially on trucks) that they would be just as useless as headlights in heavy fog; rear fog lights are rare, except on European built cars.
Apparently there is a law that requires all Subaru drivers to have their front fog lights turned on all the time; this law is obeyed by many trucks and other vehicles too …
So while supplying the auto-up-windows MINI circuit to people this year, a number of buyers have asked if I can do auto-on front fog lights. Originally I refused, citing the “proper purpose” of front fog lights as described above.
But over time I am getting ever more frustrated by other cars with wrongly used lights, and I have come to a “If you can’t beat ’em, join ’em” position; and in that position when I got another request recently for auto-on front fog lights, I succumbed!
I had an email from Dave, saying he wanted the “track mode DSC” and “auto-on front fog lights” features, but did not care about auto-up windows! So I was able to sacrifice the circuitry normally used for the passenger side auto-up, and “steal” it to implement auto-on front fogs instead. I needed to do some other track cuts and a couple of extra components were also needed (and of course the PIC needed different programming):
After testing the modifications on GBMINI, I shipped this circuit earlier this week and today I received a very nice phone call from Dave, thanking me for the circuit – which works perfectly for him. Another happy customer 🙂
M&I / GBMINI 
