All your wires go to one terminal?

Testing alternator
 

If you have a good Porsche mechanical shop in the area you could ask them who they send their alternators to for rebuilding . Most good electrical shops that service alternators will check them out for free. It only takes them a few minutes You would then know if the alternator was bad or you have some other issue in the car. Also, it would be nice to tell the place you bought the alternator from that you had it tested and what is wrong with it. It could be the rotors in it?

Another thing to check...the two spade connectors on the back of the alternator.
They are covered with plastic and you cannot tell if they are loose.
One of mine was loose and arcing...causing intermitten problems.
Just found it by accident at the alternator shop...was a real pita before we found it.
Tightened the connector and all is well now.

The mechanical shop just buys the remaned alt. Not sure why this is so complicated, but seams theres only 3 wires coming from the battery and ground. They only fit on their particular lug.

fan belt on tight? just kidding, your right there is not much to it. But if it is not working there must be something we are missing. Hate to have you remove the alt again but if your happy with the wiring and continuity than it must be pulled and checked out.

Good question, but It's tight.

He meant... that every wires have a different size eyelets and lug size (on the alternator) so If you forgot (like I did) to take note when you took them off, you can not hook them back up incorrectly.

Just wondering if there is anything else in the circuit that I may be missing to check. Otherwise its coming out again.
Thanks

Altanator removal
 

If you do remove the alternator again, how about taking a picture of the wiring that you have terminated now. If you could post the picture, maybe someone will see something that we are missing?

Update, I pulled alt again, took it to rewind shop to check it again just incase. He hooked it up, spun it, & puts out 14.5. WTF!!! Is it possible that the antitheft could have something to do with it? Do have power at the blue when the key is turned to ignition. I don't know what to check anymore. Many thanks for all in put. Tried to take pics, but next to impossible to get pics while alt still hooked up. :confused::confused::confused:

Old trick to get almost impossible camera shot....use a small mirror to bounce the light off.
Try putting the mirror behind the alt...and then take a shot from behind the car...it will be reversed...but there is software to remedy that.
It will help both you and us to diagnose the problem.
Bob

Bosch remans of valeo alternators are generaly junk, I dont use them. That being said, the alarm system also takes down the charging system. I would be a unusual circumstance in the case of a carerra,but could happen. Why dont you try bypassing the alarm. They were made by Hella & were problematic in 944's,928's& 911's of that era.
Howard

Alt is good so...Did you test the circuitry in the rest of the car?

Not sure with the rest of the cars circuits. Don't think that should matter, as that comes from the battery after alt has charged it. Just seams that there should be more than 12 volts at battery when car is running. Also, if the alarm was the problem, would the car still run? Like I said before, when I turn the key to ignition, I have voltage at the blue wire at the alt, no gen light, and that has to come through alarm, according to wiring diagram. I have battery voltage on the red wire. The alternator works every time I take it to the rewind shop. I have gen light when the key is on ignition and blue wire connected to the alt. Car starts good, so power is getting to starter. Not sure what a pic would show. The red wire is on the + lug, the blue wire is on the small lug it only fits, and the brown wires are on the remaining lug. Don't think there is much else to see. I watched the rewinder when he tested, he just clipped the wires on, spun it, and 14.5 every time. He didn't make any fancy connections. What am I missing?????
Thanks

Check and clean batt connections, batt ground to body, body to transmission ground strap, alt to starter red wire and lastly make sure good ground from alt. Had same problem on mine and turned out to be alt to starter red wire. Was getting ~ 12.5 volts, now 14+ with changes.

Try a different volt meter. I had trouble with a cheapie volt meter once. Showed that the alt. on my farm tractor wasn't charging at the battery. Had the alt. tested and it checked out fine. Put it back on and same thing..... not charging. Got my other VM and and it showed a good charge from the alt. Put a new battery in it and all is well again.

I have checked the bat to chassis, the tranny to chassis is new, battery terminals all clean. Havent done the starter positive , or the alt to tranny ground. I didn't know if I should loosen the bolt on the block. I use 2 volt meters, 1 a digital Fluke, the other an analog, both contractor quality, get same reading on both. Even if not accurate, I'm getting half a volt less when the car is running, than when I check not running. The battery is new & fully charged.
i'll have to lift the car and check the starter connection, but leaving for vacation Monday, so might not do till I get back.
Please keep any ideas coming, just incase .
Thanks very much
Cheers
jack

Have you pulled your dash Gauge to see if there is a loose terminal(s) back there?
What voltage at 3000 rpm? You mentioned 2000 rpm, maybe the regulator isn't kicking in at lower rpms?
What rpm/speed did the shop use? What load did they have on it?
A regulator can show good output unloaded but as soon as it is burdened it can fail.
Charge the battery fully before testing with a good battery charger that will indicate 100% charge to reduce the burden on the system.
Disconnect battery and test the resistance of the wiring between the battery and the alternator wires. Both grounds and hot wires.

I had an alternator issue with my '83SC so after checking all the wiring, I took it to a rebuild shop to have it tested. They said it was fine. I told them to test it again and make sure it was under a load .. again it tested fine.
I told them what a PITA it was to take out and being that it was 28 years old, just completely rebuild it anyway. The guy disagreed and said it was not my problem. I insisted they rebuild it and it solved all my issues.

Bottom line .. being that you've checked the wiring, it sounds like it's time to try a different good alternator.
just my $0.02

Have a nice new year everyone.

Kind of a Sherlock Holmes way of looking at it...but WTF? I agree....try another alt....