Re: #12 fuse problem continues! :(

[steveb@newkla.kla.com (Steven Buchholz)]

Steve D. wrote:
>   Last week, fuse #12 (controls inst. panel, fuel/tmp gauge, oil/volt 
> gauge, turn signal) blew. So the next day, I checked and retaped the 
> wires in the trunk and put a new fuse in. Everything was fine for a week. 
> Then last night on my way to work it blew again. So today, I went back 
> over the wires and tried another fuse. As soon as I started the car, it 
> went out again. :(  I'm at a loss as to the cause. The wires at the 
> trunk hinge seem ok, (well, taped and unexposed) so I don't *think* the 
> problem is at that spot. Everything was working fine before this, so I'm 
> not sure why it all of the sudden appeared. (Aside from the car being an 
> Audi! <G>)

Did the fuse blow immediately when the key was turned on?  Was the transmis-
sion in reverse (or did the fuse blow when you selected reverse)?  There may 
be a short in the wiring to the back-up lights.  Otherwise I'd recommend 
pulling S12 and use an ohmmeter to find the short.  You should find that one 
terminal of S12 has 12V applied when the key is on ... measure the resistance 
of the *other* terminal to ground after turning the key off.  You should find 
a very low resistance.  You will need to follow the wiring to the various 
endpoints to find the short otherwise ... I don't know which wires are in 
the trunk wiring harness, but it may be possible that there is a ground wire 
inside, meaning that simply insulating the outside will not solve the prob-
lem ... look for brown wires in that harness. 

Of course you could always hook up a chunk of wire in place of the fuse and 
look for where the smoke is ........ ;)
> 
>    Until the cause it found, would it hurt to drive with the fuse out? I 
> know the turn signals don't work, but other then that it seems ok.

>From the wiring diagram it would appear that neither your cruise control nor 
any of the instruments (tach, fuel gauge, idiot lights, etc.) will work when 
S12 is blown.  You back-up lights and turn signals will not function either.
The car looks like it would run, but you wouldn't know if you lost oil pres-
sure, etc.  

Steve Buchholz
s_buchho@kla.com