I don't believe in the search function on this site, because everyone recommends it and I'm not swayed by peer pressure.
So if there's a write-up similar to this already, ban me.
I was driving behind an E39 yesterday, and noticed that the brakelight section of our taillights isn't very big, and really isn't too visible either. ...so I got to thinking, I remember seeing a blank socket on my taillights that is reserved for a rear fog light, which is not commonly found on E39's in the US.
Why not make it another brake light?
Here's how you can do this simple mod:
First, you'll have to remove your taillights. Start out by unplugging and removing the covers that carry the bulbs. Notice the empty socket on the bottom row. This is reserved for the factory rear fog light bulb.
Next, remove the lenses. There's 4 8mm nuts holding each lens to the car.
If there is no hole for that fog bulb in the lens, you'll need to drill one.
I used a 1" hole saw bit for mine.
An air compressor will come in handy to blow any plastic shavings out of the lenses once they have been drilled.
Now take a look at your bulbs. On the OEM lights, the grounds are all connected through a network of metal rails, so all you will need to do is jump the positive rails for the fog lights to the ones for the brake lights. I used a small piece of 18 gauge wire and soldered directly to the positive rails. The ones you will want to connect are highlighted below.
Once they are connected, just pop in some bulbs (they use the same 21w bulbs that the brake lights use). Put everything back together and you're done.
Last edited by defaz; 12-22-2008 at 02:00 AM.
soooo... now ur rear fog light is a brake light-
i can't stand ppl that drive with their rear fogs on...
I guess all those people should do this mod instead.
Pretty cool idea actually... Are there any issues with the OBC reporting any bulb failures?
looks damn good to me, nice work
Beautiful! Great alternative to putting rear fogs in there, I might just go do that wednesday
I was actually thinking about that the other day. neat mod. maybe if I get really bored.
Damn, you stole my idea.
Question: based on the circuitry, I'm assuming that the bulbs are in series, rather than in parallel. This seems like it would put too little current going through the bulbs, since they're 21W bulbs.
Or do they not have a common ground before the power source?
Also, do you have a clearer, higher res pic of the leads that you soldered a wire between? I'd need something better than that before I'd feel confident doing this myself
Thanks in advance, and looks great!
2009 MCS 6 speed
we do it on our Audis as well,
If someone is tailgating you on the highway, hit the switch and theyll back off w/o you having to brake
i wish i could do this, but i have no soldering tool!
another question: do you think this could be done with quick disconnects instead of soldering?
2009 MCS 6 speed
I'll get the high res pic tonight...
ok gonna sound silly, is there any way (even just for the moment) to do this mod with out soldering (i have depo tails)... if that helps
the only way to do it without soldering is if your depos have a plug coming out of the light housing with some wires attached... On my last aftermarkets I was able to cut the lead going to the fog bulb and attach it with the standard brake bulb and it worked just fine...
...But if those depo's have the plates with the metal rails like the factory ones, you're stuck having to solder unfortunately, unless you can get some sort of pin for the factory side of the plug where the fog light wires would have been..
1.So people can see you clearly as they drive up behind you is the purpose, sometimes the fog hits quite fast and the fog lights gives you a little extra distance to be seen in.
Im not saying its used daily, but i have used them a few times when you have not seen the road more then 2ft in front of you.
Your point about not driving under thoose conditions is valid, but if you do get caught they are quite good to have.
The problem with thick fog might be a non-issue in some parts of the world and there it would make perfect sense to use it as a extra brakelight.
unmodded and almost fully loaded .
The depos use the same assembly in the back, you dont actually replace that part, however it makes this mod easier since the fog light hole is already pre-drilled.
On Porsches, only the driver's side foglight turns on. The same thing on Mercedes-Benz. I remember thinking what's up with Benzes always driving around with broken taillights (brake light stuck on) and mentioned it to my other bro that drives a Benz. He corrected me and told me that they are the fog lights. I noticed on his light switch that one click (pull) turns the front fogs on, and two clicks turns the rear on. Most benz drivers probably dont realize that they are turning on their rears as well.
On Audis I noticed that the rear fogs are on both sides (passenger and driver). Does anyone know if the BMWs in Europe have them on both sides or just one side?