SOLVED (partially..) Re: Dash lights w/ failed alternator?

[Sean Shoemaker]

Rob,
  Deja Vu, all over again!  At least it sounds that way to me.  You can look
back through at the "Alternator Question" posts, but it sounds like you may
be having the problem I was.  Your dash lights may (and I use "may" heavily
here) be causing your alternator problem.  I did not see anymore posts on
yours so I am adding this.  If you kill another alternator I would very
closley inspect those dash wires, that is where my problem was.  A rather
innocent little wire going to the Headlight switch lamp.  The 4 amps was
exactly the draw I was seeing.

    I had asked if there was anything in the car that could kill the
alternator and I have found that the answer is yes.  If my understand of the
circuitry is correct and the "exciter" wire needs to see voltage before it
will apply a draw to the alternator then it makes sense how this could
damage the alternator.  Repeatedly I was told that the only way to damage an
alternator was to run it without a load on it.  Well with that circuit not
functioning it sounds like that is what happens.

    Sounds like your problem may be a bit different that mine, but the big
clue on mine was the alernator light not coming on.  In my case the path was
not there.  You obviously have something there to account for the draw.  I
also don't know what platform you are dealing with, so Huw will probably be
able to tell if our problems are indeed related.

    I hope this helps.
-Shoe
'84 Coupe GT WE(5spd)


> > You should disconnect the battery ground cable, hook it back up with an
> > ammeter in line (most multimeters have a current setting).  Start high,
> > using the one rated at 10 amps, note the current draw with everything
> > off.  If it is more than a 100 mA or so, start pulling fuses - see if
> > removing one makes the current drop a lot.  If it does, you at least
> > know what branch of the wiring a short or malfunctioning device is on.
>
> Thanks, Huw.  Did this and found a 4.5A(!!) draw. Battery dies so fast it
> was hard to detect any change when fuses were removed.  The small effect
> of removing any fuse told me this huge short was someplace unfused, which
> pointed me to the alternator.  The new alternator was *also* bad.
> Replaced it (autozone guys were great about warranty stuff) and now we're
> running fine.
>
> There's still a 300ma draw- likely related to the dash lights that still
> come and go at random, but the car's running again. Hopefully I'll find
> the rest of it soon.
>
> --
> --------------------------------------------------------------------------
----
>   Rob Deis                  "Let the people know beforehand what the law
>   MiB3347                      is and what they are to expect."
>   rdeis at io.com                              -- 18th Congress, Rec. 75
>