Subject: Electrical / charging system woes
From: Marc White <traveler@southwind.net>
Date: Tue, 05 Oct 1999 01:35:43 -0500
X-Message-Number: 14



Ed Scherer wrote:

> OK, folks.  I think I messed up over the
weekend.

Hi Ed:

I was reading this and thought about the battery
all along, until you said it was only 6
months old.

I am still thinking battery, although it may be
diode toast in the alternator.  First I would
test further on the voltage drop, this sounds like
most of your problem.  Eliminate the stereo
work as a possible culprit and make sure you don't
have a draw pulling your battery down.
Have the battery checked to be sure all is well
and there are no dead cells (sounds like it).
Electrolyte and load tests.

Second have the wiring inspected and grounds
cleaned (there are a lot!).  You can do a lot of
this.  Really check the wires over well, wiggle
and shake, unscrew the jump connector and file
down the leads on both sides (big red wires and
connectors) then spray with contact cleaner.
Open the multi-plug behind the jump post and
wiggle and inspect all those fourteen or so
wires.  Look inside the connector posts for signs
of corrosion.  Check the grounds to the
engine. File them along with the battery ground
strap and terminals.  Get under the car and
clean the starter contacts and more grounds.  Go
to your fusebox and remove all the relays
(be easy with them). Inspect and clean contacts
and spray.  You might swap the horn relay for
the starter relay as a test (corroded or dirty
starter relays have been known to cause voltage
drops (especially as you describe the starting
behavior), but clean them all, maybe replace
the corroded (most all) fuses while you're at it.
This is a real good idea if you plan to
keep it for a long time.

Third (if no joy) have the alt checked for output
and function.  You should be getting very
close by now and have a clean sparking shark
(sensitive electrical sensing systems)!  The alt
can be rebuilt or serviced fairly economically by
even local auto elec shops, or just buy a
new or rebuilt one.  Check with DR or 928 Intl or
DEVEK on comparative costs and their
experiences with the options.

If this doesn't do it, you might have a tired or
worn starter.  Check or replace (depending on
the history).  Same thing on rebuilt vs new, check
with the pros.

If this doesn't fix it and you're still sober, the
ignition switch itself can be defective or
worn...or corroded or dirty.  You can swap with a
known good one in about 10 minutes with
little fuss.  Not the key part, but the socket
that plugs into the back of that with all the
wires.  It just removes and hangs down, you can
actuate it with a phillips head screwdriver
for operation.

And relax, you probably didn't harm anything by
using the jump post.  I seem to recall that
the manual recommends them for jump starting, and
it sure is convenient.  I have done that
same thing for about eighteen years now with no
bad effects (the 81).  Of course there is no
"brain" like the later models, but I have done it
on them too (87 and 88).  I think if your
electrical system is in good shape, this won't
hurt anything if done properly.  It may also
reveal a weak link, perhaps what is happening to
you now.

If I am wrong here, some of the experts please
correct me, but my experience here is not
negative  ( ;-)  ).  (ouch)

It may take some sleuthing, but it shouldn't be
too bad.

Let us know please, I have seen a lot of this
lately...  :-(.

Marc White



From: Wally Plumley [wplumley@bellsouth.net]
Sent: Sunday, November 26, 2000 9:34 AM
To: Betsy L. Jeffery; 928 Owners club
Subject: RE: [928OC Public] Electrical Issues Galore

At 08:36 AM 11/26/00, Betsy L. Jeffery wrote:
>Thanks to all who have replied.
>   If I see nothing obvious after
>checking the wiring to/from the alternator, do you, or anyone else on the
>list, have some procedures to test the alternator itself before I invest in
>a new one?


Testing for an intermittent fault is one of the more frustrating things to 
do on an automobile. You could take the alternator to an electrical shop 
ten times and have it tested each time, but if it doesn't fail during 
testing, you still don't know anything.

There are two ways to solve the problem.

1) Throw money and parts at it until it is solved.
a. Take it to a Porsche dealer and tell them to fix it. Three months and 
$6000 later, it may be fixed.
b. Give us your credit card number, and we will ship you parts until the 
problem is fixed. We will start with an alternator.

2) Test and check until you find what is wrong, then fix it.
a. Hook an electrical load and a voltmeter to the car, and either have a 
helper or put them where you can see them while you are under the car. Get 
under the car and start pulling and tugging on wires and connections. If 
there are any changes in the load (such as flickering in a headlamp bulb) 
or the voltmeter, zero in on that area.
b. Hook a voltmeter directly to the connectors on the back of the 
alternator, run the (carefully protected) wires into the cockpit, and mount 
the voltmeter where you can see it as you drive. Drive the car until the 
problem occurs, and quickly check the voltmeter. If the voltage is normal 
or higher, the problem is in the wiring. If the voltmeter is low, the 
problem is in the alternator.

There are other tests, but you get the idea.

Wally Plumley
928 Specialists
www.928gt.com