Alternator Question - resolved - Victory Dance in my driveway!

[Ben Swann]

Sean did the victory dance in my driveway today!

We finally got the wiring diagram figured out - how things should work that
is, with the helpful suggestions and feedback from several listers.

The key information that we did not grasp until recent posts is that the D+
or feild exciter wire on the alternator had to have a path through the Alt
warning light (or some other possibilities, which get complicated).  Sean
installed the new alternator - several others previously were marginal or
bad confounding diagnosis - even a newly rebuilt unit.

We now knew the first thing to look for was if the alt warning light is not
 on with the key then isolate that problem.  Seeing there was no light,
Sean made quick work to find the culprit - the blue/black wire was
disconnected from the back of the instrument cluster - aha!  Sean made a
quick solder repair and Viola!  13.8V with engine running.

We made short work of resolving a separate problem of the car cutting out
when warm, originally attributed to lack of charge.  Some mixture tweeking,
etc. and the engine purrs.

Congratulations Sean!  Your persistance finally paid off.  I know I will
miss car number 8 in the driveway, especially now I've sold the black
wagon.

Ben

[Richard,
  Thank you for the help.   I am on my way now to pick up the new alt.  As
I
mentioned before I was concerned that there may be something in the car
that
was hurting the alts.  Perhaps it was me, but at least you have given us
something to think about.  I will have to confer with Ben to totally grasp
the concept, but I think I am getting it.
-Sean

----- Original Message -----
From: "Ben Swann" <bswann at worldnet.att.net>
To: <rick-l at rocketmail.com>
Cc: <quattro at audifans.com>; "'Huw Powell'" <human747 at attbi.com>;
<shoemakersp at comcast.net>
Sent: Thursday, September 12, 2002 12:11 AM
Subject: RE: Alternator Question
> Richard,
>
> Thanks, that is helpful.  I am working off my recollection of the 4000 q
> wring diagram.  I happened to have the 5000 series one with me.  The 5000
> ones refer to the exciter wire as D+.  I did not see that on the '84 4000
q
> diagram.  That wire appeared to ultimately route to ground.  Of course
> current tracks were jumping across multiple pages, so it wasn't clear.
 As
> best as I could tell, operation of the engine closes the oil pressure
> switch whereby the exciter wire gets enable to ground.  Perhaps we read
the  diagram wrong <snip>
> Thanks again for the reply as it helped my understanding enough to go
back
> and recheck the diagram and perhaps I'll be able to tell how the
> exciter/feild wire is supposed to be actuated.  I'll advise Sean to
double
> check before trying the new alt.
<snip>