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Old 03-12-2014, 07:42 PM
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single wire alternator electronic gremlins!!!

Hi y'all,
I'm re-wiring a 68 Chevelle SS396 clone, who's previous late owner never quite finished. I noticed he installed a brand new 100amp alternator to replace the original 40amp still in the trunk, they look identical in every way & have the same 1 big wire connection plus a smaller male 2 wire plug wrapped together in a harness that connects to the bottom rear of alternator which has "F" & "R" stamped on it, the wires in the plug are white & dark/blue/blck? I accidentally pulled the 2 wires coming out of a harness loose from butt connectors that go to the male plug to alternator. The harness is a d.i.y & seems to go partially to the MSD 6AL ign.box & firewall..hard to tell exactely. My dilema is the big one is still attached but the two off the harness are the same color, does anybody know what the 2 wires in the plug to the alternator go to or better yet how to figure out which one goes back to which inner plug terminal? Could it be one has power when key on or some other way to tell? Or perhaps they can be reversed which doesnt sound logical..much appreciated!!!!!
boulonman

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Old 03-12-2014, 07:58 PM
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Your instinct is correct, you can tell which wire is the #1 terminal and which one goes to the #2.

With the key OFF, the #2 terminal will be hot and the #1 will be dead. With the key ON both will be Hot.

With out knowing which type alt you have it's difficult to tell you which terminal is #1 or #2 on the alt. If you could post a picture of the casing showing the terminals etc.....

Here is a conversion that Doc Vette posted some time ago
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Old 03-13-2014, 12:53 PM
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Quote:
Originally Posted by EOD Guy View Post
Your instinct is correct, you can tell which wire is the #1 terminal and which one goes to the #2.

With the key OFF, the #2 terminal will be hot and the #1 will be dead. With the key ON both will be Hot.

With out knowing which type alt you have it's difficult to tell you which terminal is #1 or #2 on the alt. If you could post a picture of the casing showing the terminals etc.....

Here is a conversion that Doc Vette posted some time ago
Thank you kindly EOD Guy!
That definetly is a huge help, (much better than a 50/50 chance!!! ) I could remove the alternator to take a pic of the teminal plug hole, but this may help: The female inner terminal in the alternator is located at the bottom rear of the Alternator, it has 2 prongs that match the 2 wire connection going in, above the opening are the capitol letters "F" and "S" stamped in the alt. casing (F is on the left, R is on the right from the driver seat perspective.
Also the 68 Chevelle w/383 stroker has a 1st gen. MSD 6AL ignition module box to which one of the wires go to, the other is lost in another home-made harness which contains the horn relay wire which looks melted & repaired by splicing a new wire directly from a mickey-mouse dash horn button. I know its pretty cheezy work, but considering the ridiculously low price paid for this 68 SS396 clone w/pristine body/ paint & chrome/200R 4spd auto trans/H.D 4 link 12 bolt posi .410 rearend/ladder bars/Hotchkins sway bars/upgraded power brakes/classic ralley rims w/decent rubber..etc..etc I cant complain too much having to decipher all the cheap quick fixs probably done by a automotive-challenged 3rd party, who inherited the late ex-owner's 68 before he had a chance to complete his resto 100%.
That being said, I'll go by your helpful electrical schematic, & figure out the correct connections.
I'll drop you a post with the results when done.
Again, your time & knowledge is much appreciated!
peace, Alan
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Old 03-13-2014, 04:09 PM
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Alan, the best thing I did for my 67 Camaro was switch over a to an internal regulated alt using the Doc Vette diagram, easy day. The next best thing was to install a "Painless" rewire kit, it took me a couple three weekends to install, test and verify. The absolute best thing I ever did for her. Gone were the previous owners "fixes" the electrical gremlins and dim headlights, since then I've done many more and every time......... nothing but gratitude from the owners.

There are many kits on the market and everyone has their fav, I tend to go with the painless, although they are not the cheapest, I'm satisfied with the quality and ease of installation along with customer service.
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Old 03-13-2014, 07:38 PM
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I agree with the rewiring a car as one of the best things to do for them. It is peace of mind and not as likely to burn your car to the ground with new wiring
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Old 03-15-2014, 10:50 AM
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One wire alternators belong on tractors

Rewire and install an internally regulated GM alternator and forget about it.

Vince
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Old 03-15-2014, 11:56 AM
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He is installing a 3 wire, just confused as which wire went to what terminal.
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Old 03-15-2014, 12:12 PM
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Quote:
Originally Posted by EOD Guy View Post
He is installing a 3 wire, just confused as which wire went to what terminal.
T.Y EOD Guy,

I was unsure if I was indeed installing a single wire, but you clarified that by replying to 302Z28's post claiming single post alt. are for tractors. Which I'm sure he has a valid point. That being said, I followed your diagram & checked which wire was hot/key-off, and I'm happy to report she started right up and is charging normally, alt.dummy light goes off when engine runs, all is good!! Thanks again, and I agree replacing the entire harness with a painless wiring kit is the best way to eliminate all present and future electronic gremlins that occur due to a 40 year old electronic harness!!
happy motoring, Alan
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Old 03-15-2014, 12:25 PM
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Important thing is you got it fixed.
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Old 03-18-2014, 03:09 PM
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Important thing is you got it fixed.
Thanx EOD Guy,

I couldnt agree more!!! Its truly a blast driving through my small city, since I have yet to see another 68 Chevelle in any condition!!
thanks for all your comments, every little bit helps when youre green!!!
regards, Alan
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