Alternator issue... kinda lengthy.. help please? :)

[Blackbird 13]

Hey ya'll.. bought a 1990 Eagle Talon AWD at auction (M/T, Power everything.. $850 if you're wondering), and drove it about two months before my alternator went out. Dead.. completely dead, left me stranded. I jumped the car.. got enough power to limp it a mile or so to my aunt's house in the middle of the night with no lights. Anyway.. went back with a new battery, got it to my friend's auto shop, and we replaced the alternator, with one from a 2.0 Non-Turbo, A/T car. Not an exact replacement.. but it worked.. or so I thought.

So, last night, a month later, I started getting dim battery and brake lights on the dash at 2000 RPMs or under... a quick check to the cigarette lighter with a voltmeter showed I wasn't charging. I got the car home (thankfully), and went today to a junkyard, where I purchased an alternator off of what was a running 1990/91 Plymouth Laser Turbo, M/T, Power Windows/Doors.

Got back home, and I noticed upon removing the old one that the old alternator (remember, the one that came off the 2.0 Non Turbo A/T) had only one place to hook a ground up to, whereas this one has two (but I only have one ground wire). So.. I installed the alternator, after a lot of hassle, hooking the ground terminal to the prong furthest back. Also.. on my car.. it seems someone did a little rigging. There are two wires going into the connector, and there is a loop end connector on a third wire for ground.. but there's also a fourth wire coming out that has no end (taped up end actually), and it's not been hooked up at least since I've owned the car (Feb/March-ish).

Anyway, I went to go hook the negative terminal back to the battery. Upon doing so.. sparks.. and then nothing. No lights, no power to the car.. honestly haven't tried to start it yet, but no other power. Voltmeter on the battery says it's at 12.24-ish, if my memory serves me correctly. Checked the fuses under the hood.. the alt. fuse is fried.

Now, I'll replace the fuse.. but my question is.. why? What happened that friend the fuse? Is it that the ground isn't hooked up properly? (remember, it's on the furthest towards the driver's compartment of the two possibilities..) Anyone know what could have suddenly caused the fuse to be fried?

 

[steve]

What ground. There are no ground wires connected to the alternator. It gets grounded by the mounting bracket.

There is one white wire(s) connected to the insulated stud and that's the output called B+ since it goes to the battery positive (by way of the alternator fuse). The two other wires in the plug are to sense the voltage and to provide power to start the alternator field coil.

Also in the same harness is the wire for the power steering pressure switch.

Steve

 

[Blackbird 13]

What ground. There are noground wires connected to the alternator. It gets grounded by the mounting bracket.

There is one white wire(s) connected to the insulated stud and that's the output called B+ since it goes to the battery positive (by way of the alternator fuse). The two other wires in the plug are to sense the voltage and to provide power to start the alternator field coil.

Also in the same harness is the wire for the power steering pressure switch.

Steve

Thank you much, that would explain what the hanging wire is....

.. and I apologize for my stupidity, this is the reason I'm not an auto mechanic.. but I am learning. So.. why are there two studs on the alternator, and which should the B+ be connected to?

 

[toybreaker]

The correct stud for the battery positive has a little isolator insert. It's located towards the front of the car. The stud is 6mm, and has a 10mm jam nut to keep the stud from turning.

I can understand your confusion as some alternators have another 6mm stud that looks just like it,...and some 1g's have an additional 4mm stud that held the harness/harness locking plastic isolator....

Just be sure the one you're using for the battery connection has the isolator plastic dingus insulating it from the case, and you'll be good to go.

Also don't go crazy tightening the nut, or you'll turn the the stud, and that will create another issue altogether.

 

[steve]

This is a 3000GT/Stealth alternator but it's close enough.
The B+ stud is only thing sticking up on the back. It has a brown insulator and nut next to the plug

You must be logged in to view this image or video.

This image is from the alternator rebuild page on the Stealth316 site.
In case you want to know more about the alternator.

Steve

 

[Blackbird 13]

The correct stud for the battery positive has a little isolator insert. It's located towards the front of the car. The stud is 6mm, and has a 10mm jam nut to keep the stud from turning.

I can understand your confusion as some alternators have another 6mm stud that looks just like it,...and some 1g's have an additional 4mm stud that held the harness/harness locking plastic isolator....

Just be sure the one you're using for the battery connection has the isolator plastic dingus insulating it from the case, and you'll be good to go.

Also don't go crazy tightening the nut, or you'll turn the the stud, and that will create another issue altogether.

Thanks much, that explains everything.. positive to ground would be why I blew the fuse in the first place...

And thanks Steve, as now I know what that other wire goes to... doesn't make me as uncomfortable that it isn't hooked up!

EDIT: One last thanks to the moderator who gave me a warning for bumping this... I've seen the error of my ways, and will strive to be a model DSM forum poster from now on.....

... and on a more serious note, my apologies for doing so. I should have read the rules against bumping.. but y'know, it frustrated me that not a single person had viewed this post. Obviously, I had an issue that I needed help with....

Everytime I come back here, I end up saying how something is restrictive. This is easily the most restrictive online community I am a part of, and I'm only here because of the weatlth of information to be had. The forum leaders and moderators, IN MY OPINION, are far too strict, and this community is WAAYYY too uptight and arrogant at times about a lot of things. Live and let live.. do your thing, and ignore something if it doesn't pertain to you. It's not all about warnings and bans all the time people.



But yeah, sorry for the tangent, thank ya'll for the help!