Any Fuse-Blowing Diagnostic Tricks?

[Sam Letzring]

I have had similar problems with my 86 4KCSQ- not necessarily the same
circuit- but plenty of others.

My biggest problem has been with the cable bundle that runs to the lights,
etc. on the trunk lid- the cable bundle has broken there several times and
shorted out- ditto with the cable bundles in the doors for the electric
windows- there are plenty of hidden places where the wires can rub and
short.

good luck

Sam Letzring
New Mexico
86 4KCSQ with over 500kmiles
----- Original Message -----
From: "gwbutler" <gwbutler at net1plus.com>
To: <quattro at audifans.com>
Cc: <george.butler2 at verizon.net>
Sent: Sunday, January 16, 2005 6:07 AM
Subject: Any Fuse-Blowing Diagnostic Tricks?


> Hello all,
>
> My 84 4ksq has been entertaining an electrical gremlin for a very long
time.  I've made numerous attempts to get to the bottom of the problem and
each shot at it makes the problem more perplexing.  I'm hoping that a lister
has resolved the indentical issue.
>
> The problem is that the car keeps blowing the S17 fuse (supports the
blower, radio, antennae, cigar lighter, glove box light, etc).  What makes
the problem complex is that the car doesn't blow the fuse consistently.  I
have gone months without blowing the fuse, only to hit a period (like now)
where the fuse blows everytime I use the car...but not always immediately!
>
> Case in point: A few mornings ago I; replaced the fuse, started the car,
turned on the blower (to position "2"), drove toward work for approximately
15 minutes, turned on the radio...and everything was fine all the way to
work.  After work I; started the car, (blower sitch was still in the "2"
position) the blower worked, turned on the radio after only two minutes this
time, and the blower died (blown S17)! Sometimes the fuse blows the second
it is placed in the holder...even with the car off.
>
> To date I have:
>
> . placed an in-line fuse on the "hot" wire to the power antennae (BTW, the
antennae is a Blau-provided OEM replacement...and the problem didn't exist
prior to replacement...fuse still blows with antennae completely
disconnected)
>
> . removed/disconnected every device on the circuit and STILL blown the
fuse...really!
>
> . replaced the blower control switch (with one from my old 84 4ksq
cannibalization unit)
>
> . replaced the enormous resistor supplying the blower speed selection at
the blower motor (used unit...same symptom)
>
> Does anyone have any clever diagnostic "tricks" that they use to
specifically isolate intermittent shorts...or intermittent over-currents?
I'm pulling my hair out on this one.  Any suggestions? TIA
>
> Regards,
>
> George B.
> Massachusetts
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