Help!!...Need an electrical Guru

I'm hoping someone will have some insight to my problem. I have an '82 SC used as a daily driver. Today after a short drive I noticed the battery light stayed on with the ignition off and with the key removed. I disconnected the battery, inspected connections, then hooked it back up. The light still came on. Goes out when car is running though. Weird!! I pulled the guage but all connections there appear to be okay. Starting power seems fine so I doubt it really is a low battery. I hate to say it but I can't find the alternator on my car. Jiggling key switch didn't help either. Any thoughts guys?

Jamey
'82SC
'84 928S

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try adding aother light bulb in there and see if the problem persists. also check that everything else electrical is turned off when you turn the car off...

there shouldnt be any flow of electricity (maybe except to the clock) when you shut off your car

Jamey
I would guess the electrical contacts inside your ignition switch are not opening again when you turn off the key. Try another switch if you can.
Les

your alternator is the culprit. a diode problem, feeding power back to the light. have you hooked up jumper cables backwards lately?

No I haven't jumped the car at all. No new electricals added either. The CD player did start having a few problems about 3 days ago(cd's wouldn't play unless I ejected them and then reinserted). Would the diode allow current back to the light even with the engine off/key off and removed?

Well I just went out and started the car. When I disconnected the positive battery cable the engine immediately died. So, unfortunately, I think John Walker is right in saying my alternator is bad. Darn, I was getting my front seats reupholstered next week!! That may get put off now.

If your alternator's wasn't dead, disconnecting the positve battery cable while the engine was running probably did it. Next time, don't do it.

Sherwood Lee
http://members.rennlist.org/911pcars

Yup, alternator is having problems. Here's a table from one of the tech articles on the site:

The following guidelines are useful for troubleshooting your alternator:

Alternator indicator lamp is on with the ignition key off.
· Alternator has failed, and diodes have shorted out. Replace alternator and in the meantime, disconnect battery to prevent it from becoming completely drained.

Alternator indicator lamp does not light when ignition key is turned on.
· Alternator bulb has burned out.
· Regulator has failed
· DF wire is disconnected or broken from alternator
· Alternator has failed, and internal windings are open

Indicator lamp remains on after engine is started and running above 2000 rpm
· Regulator has failed
· Battery lead to alternator has been disconnected
· Alternator is not firmly grounded
· Alternator internal bushings are dirty or worn
· Alternator is bad

Indicator lamp is dim after starting, and gets brighter as engine rpm increases.
· Battery lead to alternator loose or bad
· Ground connections are bad
· Battery is bad
· Alternator is bad due to open diode failure

Indicator lamp is dim after startup, but eventually gets dimmer and goes out when engine RPM increase.
· Low charged battery
· Poor connections to battery

Indicator lamp is dim after startup, and gets dimmer as rpm increases, but never goes out.
· Regulator has failed
· Alternator is failing

Also see our alternator replacement article:

http://www.pelicanparts.com/techarticles/911_alt_replace/911_alt_replace.htm

Good luck!

-Wayne

The alternator is inside the engine cooling cover, behind the cooling fan. The fan is mounted on the alternator shaft. A bit intimidating at first, but not that bad to remove. A little tight on room while the wires are connected.

Take the alternator to an alternator/generater shop and save some $ for the seats.

Good luck

OK, I've almost got the alternator out. On the back of the alternator mine has a metal cone shaped cover that encases the back of the alternator. It looks like I have to remove this to get to the back of the alternator and disconnect the wires.This metal shroud has what appears to be several cooling fins on it. The tech article that Wayne posted does not show this shroud around back of alternator though. Since the length of the alternator wires that go into the back of the shroud aren't very long it looks like I will have to tilt the alternator/fan assembly and gently turn it to be able to remove all the bolts that hold this cone shaped shroud on. Has anyone ran into this situation before?

You are right on schedule.

Actually they are nuts that you must remove, but you know what you are talking about. Manuver the alternator around and work the nuts with a 10mm wrench. The cooling cone is not connected in the center bottom, but is on all the rest.

Once the cone is off I pull the tighest wire first to start making room. You might make a note of where the wires go, but if not don't worry. Putting them back in their place will be the easiest part of the job, you'll get lots of help if needed.

I assume the fan is still connected. I use a large gear puller, if you don't have one there are many ways to "skin that cat", just protect the threads on the shaft whatever you do.

Load the alternator and your seats in the wife's mini-van and carry them to the alternator shop and the upholstry shop, and by next weekend you can redo everything you un-did this weekend, only have much more fun.

Good luck

Be sure to make an index on the cone and the alternator so you get it back on in the correct position. That deflects cooling air to the left side cylinders and is critical.

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Tyson Schmidt
72 911 Cabriolet
92 C-2 Cabriolet

Allright!!, I got the alternator back from the shop today. He only charged me $80. It took about 1 1/2 hrs to get everything buttoned back up. Everythings working fine now. It was parked for only 3 days while we waited on parts to arrive, but Geez that was a long 3 days. Next week I'll start the brown to black interior conversion. Then on to the AC fan motor on my wifes 928. Aren't Porsches fun!! A gratuitous thanks to Wayne and all you guys for the helpful advice.

www.geocities.com/jamey928/index.html


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