aiming fog lamps and general fog light questions

[RickW]

it's come to my attention that my fog lamps piss people off. Not because I drive such a sweet car, but because they apparently blind people. I've seen the info on danielsternlighting.com about aiming, with a brief mention of fog lights. To expand on that, what should the light pattern be for fogs? Mine seem to throw a fairly wide beam left and right, and I'm not sure if this is what is upsetting oncoming drivers or if they are aimed too high (which they probably are). Am I to understand that the fog beam pattern should cut off at the same height as the low beams? How far left and right should the pattern be? I think I need to toe mine in, though it is pretty nice to light up the entire road and shoulder (I live in deer country). Any insight would be great.

[adawil2002]

As general rule, fogs are mounted below the bumper. They should light up wide and low with the beam cutoff being just inside the lower low beam cutoff. They are designed for low visibility situations, they should switch off automatically when high beams are switched on. This is how they are on my 1997 M3 & the 2004 X3.

Driving lights have a more narrow directional beam and are set above the bumper, usually set ahead of the high beams to extend the range of visibility. They should switch off when switching to low beams. This is how they are on Vern.

[EddyM]

Fog lights aren't intended to provide the distance penetration that even your low beams provide. They're intended to be mounted low and aimed low so they get under the fog and reduce backscatter, which is what makes you pretty much blind in fog. The beam is very wide (75 to 90 degrees or even more) and very narrow top to bottom - projected on a wall it looks like a thin horizontal bar of light. If the fog is thick enough you can't really see very well with your low beams, then it's time to turn on your fog lights instead - and back off the speed as well.

In terms of aiming, I'm not sure just where the beam should be when projected on a wall or garage door, but maybe a good starting point would be to have the top of the beam about halfway between the top of your low beams and the ground when the car is 20 - 25 feet from the wall. If you encounter fog, use them, and if you feel they're too high or too low, you can make appropriate adjustments.

If properly aimed, fog lights shouldn't create a problem for on-coming traffic. What I all too commonly see, however, is an SUV with fog lights integrated in the bumper (which sits pretty high off the road relative to an '02 bumper or the '02 driver's eyes) running the fog lights on a perfectly clear night. I don't know if people think this is cool or are just ignorant of the real purpose of fog lights, but many are either poorly aimed (too high) or mounted way too high (on an SUV it's likely for lack of lower mounting points) and the darned things glare like the devil.

Hope this helps.

[RickW]

excellent information, thanks. Maybe I should rewind a bit a get a better education, since I was unaware of some of the finer points of fog lights. What I have is pictured below, and I see this setup on a lot of 02s. Is this stock, or should they be under the bumper? I also call them fog lights because that's what the switch on the dash says, but I guess these are set up as more of a driving light, although they do throw a narrow wide beam and do not turn off with the high/low beam switch, only the dash. Sound like I need to either A) re-aim them and re-wire to use them as driving lights, or put them under the bumper or re-aim them much lower?

[c.d.iesel]

fogs aimed to slightly lower than the low beam pattern

check the alignment of the low beams first

on level ground at right angle to a wall

[EddyM]

excellent information, thanks. Maybe I should rewind a bit a get a better education, since I was unaware of some of the finer points of fog lights. What I have is pictured below, and I see this setup on a lot of 02s. Is this stock, or should they be under the bumper? I also call them fog lights because that's what the switch on the dash says, but I guess these are set up as more of a driving light, although they do throw a narrow wide beam and do not turn off with the high/low beam switch, only the dash. Sound like I need to either A) re-aim them and re-wire to use them as driving lights, or put them under the bumper or re-aim them much lower?

I can't see the lenses well enough to know if they're fog or driving lights. You see a lot of lights mounted like yours on '02s because, in most cases, they are driving lights. When the cars were sold new in this country, they came with sealed-beam headlights that were not all that great - but it was federal regulation. Some people purchased after-market Hella, Cibie, Marchal, or Carello H-4 headlights and swapped them out; others simply added a pair of driving lights.

Fog and driving lights ARE NOT interchangeable - fog lights have a very wide beam, not much penetration (distance), are usually mounted below bumper level to get the beam under as much of the fog as possible, and in modern vehicles are generally wired so that they are turned off when you hit your high beam lights. When properly mounted and aimed, fog lights rarely annoy on-coming traffic. Driving lights, on the other hand, generally have a beam that's much narrower and either round or oval (though Marchal used to have one that was bowtie shaped - wasn't worth a damn imho), provide greater penetration than all low beams and most high beams, are usually mounted above the bumper and close to headlight level, and on my MINI they're wired so they can be turned on only when the high beam lights are on. When properly mounted and aimed, driving lights will totally blind on-coming traffic on an undivided highway - and often will do so on the Interstate as well.

Here's a link to a web page that illustrates the difference between fog, driving, and spot beams - in this case for the legendary Cibie Super Oscar.

http://www.talbotco.com/cibie_aux_lighting.htm

Notice that the fog beam has 45-meter spread and only 50-meter penetration, while the driving beam has 28-meter spread and 370-meter penetration. Also, notice that the widest part of the fog beam is very close to the front of the car, while the widest part of the driving beam is some distance from the front of the car.

If, indeed, you have fog lights (the beam will tell you), and you intend to use them as such, they should be hung under the bumper. Some lights are not intended for inverted mounting (I don't know why, but I've seen caveats about not mounting in a suspended manner), so you may or may not create some kind of problem by hanging them under the bumper. They don't turn off with the high/low switch because they aren't wired to do so - whether you elect to change that or not is up to you. If they're really driving lights (again, the beam will tell you), you can leave them where they are and again, whether you wire them to come on only when you've selected high beam is up to you. No matter how they are wired, though, I suggest you make sure they are running through a relay.

[Emyers]

Fogs on bottom, driving on top of the bumper.

Earl

74 02Lux

02 M Roadster

72 Volvo 1800ES

[RickW]

It appears that I have bosch halogen fog lights, at least from the distinctly horizontal beam pattern. Driving lights I think would be more useful so I'm looking for a set of those. If I did wire the driving lights into the high beams do you think that circuit can handle it? In other words, would it be a simple matter of taking the driving light leads and wiring them to the high beams, or am I going to need to create an entirely new fuse protected and relayed circuit? I think my dream setup would be a three option set up: low beams, high beams, and high beams with blazing inferno driving lights! (good for the fall deer season here in the mountains)

[EddyM]

It appears that I have bosch halogen fog lights, at least from the distinctly horizontal beam pattern. Driving lights I think would be more useful so I'm looking for a set of those. If I did wire the driving lights into the high beams do you think that circuit can handle it? In other words, would it be a simple matter of taking the driving light leads and wiring them to the high beams, or am I going to need to create an entirely new fuse protected and relayed circuit? I think my dream setup would be a three option set up: low beams, high beams, and high beams with blazing inferno driving lights! (good for the fall deer season here in the mountains)

You should always use a separately fused and relayed circuit to power driving lights.

There are two reasons:

1) The switch and fuse on your headlight circuit probably aren't beefy enough to handle the extra amps (two 55-watt bulbs = a bit over 9 amps in a 12-volt circuit), so you'd likely blow fuses or a regular basis or melt your switch. Triggering a relay adds only a miniscule amount of extra power draw to the headlight circuit;

2) QI bulbs work best and last longest when they run at full voltage - wiring them through a relay makes sure they get full voltage all the time.

[adawil2002]

It appears that I have bosch halogen fog lights, at least from the distinctly horizontal beam pattern. Driving lights I think would be more useful so I'm looking for a set of those. If I did wire the driving lights into the high beams do you think that circuit can handle it? In other words, would it be a simple matter of taking the driving light leads and wiring them to the high beams, or am I going to need to create an entirely new fuse protected and relayed circuit? I think my dream setup would be a three option set up: low beams, high beams, and high beams with blazing inferno driving lights! (good for the fall deer season here in the mountains)

These are what's on Vern, Hella 160s. With them and the high beams it lights up the road better than the X3s adaptive Xenon high beams.

http://www.rallylights.com/detail.aspx?ID=5010

They have a wide variety of lights to choose from.

There should be a white wire with a factory female connector with a plastic sleeve near the battery in the lighting harness that supplies power when high beams are switched on.