STILL blowing fuses

[Motor Sport Visions Photography]

In a message dated 5/17/2002 Brett Dikeman writes:

<< ...Nope, the 5000's don't have the fusible link.  It is debatable how
worthwhile it really is, however.  You rarely hear of a seized fan
<snip>

Given the seriousness of that fuse, Audi should have implemented a
supervisory circuit.  Actually, there's a darn fine idea, if I do say
so myself...the level switch for the coolant tank is conveniently
inches from right there, and I bet you could make a little relay that
went in parallel with the fuse, and closed that circuit it if the
fuse blew or corroded.  Sweet! >>

Actually, I have heard a fair number of reports over the years of fried
wiring looms in 5ktqs on the list. Several years back Dewitt (Harrison?)
did a write-up with part numbers to retrofit the factory parts from a 91
200q in to protect the circuit with a factory look. Later on Avi
suggested an in-line fuse (70a or 80a, I forget which now) that is
readily availble (which is the route I went, one fuse installed inline
to the fan, another riding along in the trunk for replacement just in
case--they're cheap.

Anyway, what a brilliant and simple idea! I gather you're thinking 12vdc
relay coil across the fuse with the n/c contacts wired in series with
one of the coolant level sensor wires? This way when the fuse is good,
no voltage differential to pull in the relay coil. Fuse opens, coil
pulls in, contacts open, coolant warning light comes on. I like it!

Only one minor detail, that shorted fan's current draw will all go
through that relay coil in the fail mode so the alert could be just be a
passing blink of an eye before the relay coil evaporates when the smoke
gets let out. Hmmm...have you addressed that yet?

Mike Veglia
Motor Sport Visions Photography
http://www.motorsportvisions.com