Alternator or just a Gremlin?

[Red76]

Ok, Here is the situation. I was driving my 76 up the coast on New Years Eve and it starting giving me issues. Started missing and sputtering left and right. Pulled over and it just died. No juice, no lights, no radio, just dead. Figured out the battery was dead. Got a jump start and made it home but still had no juice. Put it on slow charge over night and the next morning it started up right away and ran great.
Battery checked out ok so I know that's not the issue. Gotta be the alternator. Pulled it out and had it tested at a few different shops. Just my luck 50% of them said it was good and you guessed it 50% say its bad. Go figure.
Anyway my question is on the wiring. I pulled the alternator out and out of habit it took a pic of it. Just in case. I noticed the wires were wrapped in electrical tape and they had a "bulge" a few inches down. Started unwraping the tape and I found another yellow with red stripe wire that was not hooked up. What is that wire for? Does anyone know?
Like I said Im pretty sure at this point its the alternator but any advice at this point would be welcomed.

Sorry about links for the pics but I havent figured out how to ad pics yet. lol

http://s613.photobucket.com/albums/tt21 ... 164614.jpg

http://s613.photobucket.com/albums/tt21 ... 164714.jpg

[majicwrench]

You need to test the alternator with it in the car, engine running. Bench test really iffy.

[So Cal Mark]

it would be helpful to know what alternator you have. Do you still have the external voltage regulator? Does the red warning light on the tach illuminate with the key on?

[Red76]

It is the Bosch with built in regulator.
It was tested 3 ways
In car running with a meter at the battery (no good)
In car running with volt meter at the alternator (no good)
Bench tested on two different testers (One good, one bad)

I'm really thinking the alternator is bad. I pulled the regulator and the brushes looked good. Not sticking or overly worn. I'm mainly worried about what the extra wire may be and why a prior owner taped it up. So at this point I'm on the search for a fairly priced replacement.

Once I get this fixed I need to figure out where first gear went, will try to find pointers on that under prior posts.

[kmead]

Normally the yellow wire goes to the warning light and is the exciter for the alternator causing it to charge.

Although it may be the alternator, it may be even more basic. While you have things apart I would also chase through the following:

Start with your electrical connections to the battery (+ -), to the engine (-), to the alternator, the ignition switch and the brown wire into the fuse box.

Any one of these could create the situation you have described, particularly the intermittent nature of the problem.

[So Cal Mark]

since the alternator was changed to an internal regulator system, the wiring is probably not correct. Your 76 had a warning light relay along with the voltage regulator that makes the wiring connections a little tricky for an internally regulated alternator. If the alternator charged on a bench test, I'd bet it's not connected properly in the car

[mdrburchette]

That excitor wire has to be connected or your alternator won't charge. Does the alternator light in the car come on when you turn the key? Does it go off once started? If the car was changed from an external to internal regulated alternator, it sounds like Mark's probably onto something with the wiring.
Side note: When I changed mine over, it took a while for me to get that excitor light to work. My alternator wouldn't charge until I did.

[Red76]

Cant really say if its an "intermittent" problem. I have only had the car for about 10 days. Did not put that many miles on it before I had trouble. Maybe 50 or so. For all I know the seller had fully charged the battery before I bought it. Might have been running on battery power all that time.
Anyway, more info. The indicator light on the tach does NOT light up either before or after starting the car. Checked the battery cables, replaced a questionable terminal and cleaned the posts.
Here is another clue. Im not sure but I might have found another EXTERNAL regulator on the car. Its located on the drivers side wheel well in the engine bay. Looked around it and if found a disconected wire that looks like it goes to it.
On the advice of a friend I did a different test:
He told me to disconect the "field" plug to the alternator.
Start the motor.
Turn on the lights.
Cross the field terminal on th alt with the pos terminal on the alt.
Watch to see is the lights get brighter with the jumpers crossed.

Did that test also. There were no changes in the brightness of the lights.

Pics of the external regulator:

http://s613.photobucket.com/albums/tt21 ... 142410.jpg

http://s613.photobucket.com/albums/tt21 ... 142427.jpg

[mdrburchette]

Here's a print out of the conversion I did and it worked fine. It tells you just what to do with that yellow field wire.
Hope this helps:
http://mirafiori.sonic.net/faq/content/alt-upgrade.html

[Red76]

Sorry to be such a pain but Fiats are kinda new to me. Spent the past 5 years building a Jeep. Can anyone tell me if the pics in my earlier post are of an external voltage regulator? Been a long time since I have seen one of them.
The alternator I have is the Bosch 0 120 489 134 / 55A. All the sorces I have looked at say that is the stock alternator.
Pic Below:
http://s613.photobucket.com/albums/tt21 ... 201734.jpg

I dont understand why if I have the stock alternator with built in regulator A) Why would there be the extra yellow/red wire B) Why would there be an external regulator.

Side Question:
Money is a bit tight like it is for all of us. What would be the best general repair manual to start off with that wont really break the bank. Or maybe someone knows of online manuals?

[mdrburchette]

77 is when they came with the internal regulated Bosch alternator. Someone replaced your Marelli with the Bosch. It looks like they didn't wire it right. Please read the link I posted. It will explain what you need to look for. If you still have questions we are right here to help, but I'd be willing to bet your alternator is good but hooked up wrong.

[Red76]

Sounds good. Going to run it up to the Jeep shop tomorrow with all the info everyone has given. We have a guy there who is a wiz at wiring and building motors. He saw the car Sunday and was trying to talk me into just installing a 350 SB in it. LOL

[mdrburchette]

Might have to put half of it in the trunk! There's hardly enough room for a little 4 banger.

[wikkid]

Sounds good. Going to run it up to the Jeep shop tomorrow with all the info everyone has given. We have a guy there who is a wiz at wiring and building motors. He saw the car Sunday and was trying to talk me into just installing a 350 SB in it. LOL

Why do so many people jump right in with the short block conversion idea?!!! There's a guy working at my neighbor's house, and every time he sees me out in the driveway, it's his "running joke."

[Red76]

As tempting as a 350 might be............
Something tells me it might be a sin to do that to a Spider.