Fuse for brake lights keeps blowing - tech can't find problem

It's a 1998 A4 1.8 Quattro. First, they thought it was the switch, so they replaced that. Test drive was fine. Next day, blown fuse.
Yesterday they spent 3 hours ($$) examining the wiring. Couldn't find
anything wrong. New fuse in, test drive was great. Today, blown fuse. I replaced it, drove around, tried everything I could think of to make it blow (turn indicators, power locks, stereo, A/C). Working great, but I know I've got about 24 hours before it goes.
If anyone has a suggestion, I would greatly appreciate it. I'm at the end of my tether. The only solution the service dept has (re-wiring) is so horrifically complicated and expensive that even they don't want to do it.
The only other issue I'm having, but this has been going on for many months -- long before the brake light problem -- is the cruise control. It works about 60% of the time. The rest of the time it won't engage, or engages for a short period and then cuts off. Temperature and rain don't seem to play a role. Happens in the dead of winter and during hot summer days. I can live without it for now. (I mention it only in case it's relevant.) But brake lights are serious. I actually found out I had the problem by having a very angry motorist yell at me.
Please help!
If it's relevant, I live in a climate where the winters are very cold (-40C is common) and the summers can be very hot and humid.
Thanks!
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auto or manual? the auto trans may have a solenoid or relay that needs that brake light switch to allow you to select a driving range.
just a wild guess but did that tech check the wiring at the trunk lid? the earlier Audis had problems with that wiring area breaking and causing fuses to blow
might even be a bad or incorrect bulb
does anything else not work when that fuse blows?
the cruise control might be a bad switch at the pedal(s)
jmho
--
later,
dave
(One out of many daves)
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One out of many Daves wrote:

Manual.
They said they checked all the wiring "at the back"? Exact wording on the bill: "Looked at trunk area and under dash for source of malfunction. Repositioned wires to try and recreate fuse blowing."

I haven't noticed anything else not working, although I've been looking. I wish I knew out what else would be on that circuit, because it might indeed be that (other) thing causing the fuse to blow. If they haven't already, I'll tell the repair shop to replaced all of the bulbs--see if that makes a difference.
Peter wrote:

That's precisely what I'm afraid of too.
I'm driving now with the cover for the third (middle) brake light removed so that I can see in the rearview if the brake lights are working. My guess is I'll be replacing the fuse sometime later today. :-(
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hmmm does your cigarette lighter work when the fuse blows? I agree with Peter, I am thinking that maybe something else is blowing it. Maybe something that always gets power like interior lights, trunk lights maybe, etc. I knew an Audi 5000 that had a vanity light that would drain the battery down even though the bulb did not light up with the ign. off.
OK test out other components to see if they work now. Your owner's manual should tell you what that fuse protects. You might want to take that fuse out and test your other components. But I guess in time the fuse will blow and THEN you can test things to see what else does not work. ;-)
don't throw in new bulbs, but YOU can possibly inspect them. ;-) but I would think that the dealer tech checked them. 8^o
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On 16 Sep 2006 15:46:27 -0700, snipped-for-privacy@yahoo.com wrote:

I once had a similar problem, many years ago, in a non-Audi car. I discovered it when I was stopped by the police one night for driving without tail lights.
The problem in that case turned out to be a wire that was chafing on the metal part to which it was attached and, once the insulation had worn through, was shorting. On that occasion the actual wire in question was not on the tail lights circuit, but something else that was fed through the same fuse. If you have the same problem - and I hope you don't - it will be a real pig to trace.
Peter.
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Here's the latest:
Driving to work this morning, kept looking at the middle brake light (cap is off) every time I braked. Just before I got on the freeway, about 20 minutes into my trip, I braked at a light. No brake lights. I was doing nothing else at the time -- no turn signal, nada, just driving.
So....I took it to a different service place, one that I had used many times before. They just called me. After three hours labour, their diagnosis is...they can't find the problem. It is to weep....
Told the tech to replace all the bulbs in the rear (what the heck--he figured it couldn't hurt). The tech is going to drive it home and back tonight, see if he can get it to blow. Everyone says they have to "see it" happen to figure it out. Please god, let it blow.
I mentioned the (pre-existing) problem with the cruise (which is turned off, and has been off for a while). He said maybe we should fix that, see if it's related. What do you think? He mentioned replacing a "module" for the cruise (sorry, no idea what means).
Sigh.
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have him disconnect the cruise module if possible. Maybe the module is blowing that fuse if it is tied to the brake light switch.

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