1966 Mustang Alternator Wiring - Ford Mustang Forum
 
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post #1 of 12 (permalink) Old 03-16-2010 Thread Starter
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1966 Mustang Alternator Wiring

I recently had a lot of work done on my 1966 Mustang and while the engine was out, I decided to check the alternator and see if I needed a replacement or not. I took it to a local parts store and they ran the tests on my alternator and said that it was bad, so I decided to turn it in and buy a new 65A alternator. The new one is an Ultima brand and I don't know much about it - if it is a good brand or not. Well when the parts were all going back into my car, the person that did the work for me installed the alternator and associated wiring. On the new alternator, there are 5 terminals. One is BAT with a red plastic ring around it. Another is STA with a black plastic ring around it. The next is GRD with no plastic around it. Another terminal is FLD with white plastic around it, and the last terminal has no letters by it and no colored plastic around it. My battery has died 2 times since I had the car back (I've only driven it 36 miles so far). First I thought that the belt was loose, so I tightened it, but it died again yesterday. Now I was thinking that the whole alternator was bad, but when I went to remove the alternator, the wiring was as follows: There is a thick, solid yellow wire going to the BAT terminal. A white wire was going to the STA terminal, and a solid red wire was going to the terminal that has no letters by it and no colored plastic around it. From what I've seen so far concerning wiring diagrams, this is definitely not correct . I do not have a black wire with a yellow stripe, only a solid yellow wire. I also do not have a black wire with a red stripe, only a solid red wire. What I'm thinking now is that it was just completely hooked up incorrectly and I'm going to hook it up like this when I get home: Thick yellow wire to BAT terminal, red wire to the GRD terminal, and white wire to STA terminal. Does this sound feasible? I just don't want to fry anything AND would like my battery to charge while I'm driving it. Any help would be appreciated .


I finally got the engine and transmission rebuilt!
1966 Mustang
289 c.i., 2V carb
Automatic C4 transmission
Griffin 2 core aluminum radiator
Hedman headers
Dual Flowmaster 50 Series Delta mufflers
Ultra thin Spal 14" electric fan
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post #2 of 12 (permalink) Old 03-16-2010
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A simple solution might be to just buy a new alternator wiring harness to get thing back to the way they are supposed to be without too much trouble. They don't cost too much and are simple to put in. Once you have done that, the colors should match the wiring diagrams making life simple.


'66 GT, 289 4V, 4 speed w/ rally pac. A work in progress trying to get it back to as original as possilbe.
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post #3 of 12 (permalink) Old 03-16-2010 Thread Starter
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Well the new wiring is a future project - there aren't any funds available right now to buy pieces of the wiring harness . For now, I have to use what I've got. Thanks for the suggestion, though.

I finally got the engine and transmission rebuilt!
1966 Mustang
289 c.i., 2V carb
Automatic C4 transmission
Griffin 2 core aluminum radiator
Hedman headers
Dual Flowmaster 50 Series Delta mufflers
Ultra thin Spal 14" electric fan
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post #4 of 12 (permalink) Old 03-16-2010
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Try to find someone with a shop manual. The '65 Shop Manual has a picture that shows exactly what wires go to what terminals, and I imagine the '66 manual does, too. Unfortunately, I do not have a '66, and the wiring changed (the '65 had an extra white-black wire). Hopefully someone with a '66 manual will read this and help out.

Joe
'65 Coupe, 302, Autolite 4100, C4, 3.00
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post #5 of 12 (permalink) Old 03-16-2010
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Have you checked the voltage regulator because i just swapped my 289 for a 91 5.0 and the days following my battery died 3 times just like you so i bought a new alternator and it died again and it was wired correctly so i checked ma voltage regulator and that solved my problem, maybe you can try it i also have a 66 mustang

1966 mustang Wit Cammed 91 5.0 roller motor T-10 4 speed trans
whole lot of sexy
97 Cobra
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post #6 of 12 (permalink) Old 03-16-2010
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The wiring diagram for the 66 alternator is in 66MUST2.TIF in this ZIP file:

66 Mustang Wiring Diagram
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post #7 of 12 (permalink) Old 03-16-2010 Thread Starter
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Quote:
Originally Posted by Chavez View Post
Have you checked the voltage regulator because i just swapped my 289 for a 91 5.0 and the days following my battery died 3 times just like you so i bought a new alternator and it died again and it was wired correctly so i checked ma voltage regulator and that solved my problem, maybe you can try it i also have a 66 mustang
Well I'm going to try to hook up the wiring like I think it SHOULD be wired and if it still doesn't charge, then maybe I'll look at the voltage regulator.

I finally got the engine and transmission rebuilt!
1966 Mustang
289 c.i., 2V carb
Automatic C4 transmission
Griffin 2 core aluminum radiator
Hedman headers
Dual Flowmaster 50 Series Delta mufflers
Ultra thin Spal 14" electric fan
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post #8 of 12 (permalink) Old 03-16-2010 Thread Starter
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Quote:
Originally Posted by Bitter View Post
The wiring diagram for the 66 alternator is in 66MUST2.TIF in this ZIP file:

66 Mustang Wiring Diagram

I've looked at this diagram but just can't really make any sense of it. Plus the terminals on the alternator in this diagram aren't labeled, which is a big part of my problem.

I finally got the engine and transmission rebuilt!
1966 Mustang
289 c.i., 2V carb
Automatic C4 transmission
Griffin 2 core aluminum radiator
Hedman headers
Dual Flowmaster 50 Series Delta mufflers
Ultra thin Spal 14" electric fan
BoxcarJoes is offline  
post #9 of 12 (permalink) Old 03-16-2010
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Here's a pic from the 65 Shop Manual. It should be the same as yours. The thick Black/Yellow wire goes to the battery and should be the same as your thick yellow wire. See if this helps.
BTW: For future reference, an alternator wiring harness from any of the Mustang suppliers is around $20.
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66 Convertible 6 cyl automatic
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post #10 of 12 (permalink) Old 03-16-2010 Thread Starter
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Quote:
Originally Posted by 65 Fixup View Post
Here's a pic from the 65 Shop Manual. It should be the same as yours. The thick Black/Yellow wire goes to the battery and should be the same as your thick yellow wire. See if this helps.
BTW: For future reference, an alternator wiring harness from any of the Mustang suppliers is around $20.
Thanks, I think the diagram is what I needed. I was under the impression that the alternator wiring harness was a lot more expensive than that - I guess the local "Obsolte Ford Parts" place here is just very proud of their wiring harnesses. There used to be a place that was here local that was devoted to 1964-1973 Mustang parts only, but unfortunately they closed down. I say unfortunately because the guys that worked there actually knew SOMETHING about Mustangs. The people at the classic Ford parts place don't seem to know anything about the Mustang at all, and they've let me down on a bunch of parts by either not having them in stock or saying "Oh, we don't carry ANYTHING like THAT!". Oh well, ordering parts off the internet is always fun.

I'll post back later tonight after I install my alternator to let you know if it is charging my battery or not.

I finally got the engine and transmission rebuilt!
1966 Mustang
289 c.i., 2V carb
Automatic C4 transmission
Griffin 2 core aluminum radiator
Hedman headers
Dual Flowmaster 50 Series Delta mufflers
Ultra thin Spal 14" electric fan
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The picture Fixup is the one I was talking about. The '66 wiring diagram does not include the white-black wire to the stator terminal, so I'm unsure if the white wire still goes to the field terminal or replaces the one at the stator.

Joe
'65 Coupe, 302, Autolite 4100, C4, 3.00
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post #12 of 12 (permalink) Old 03-16-2010 Thread Starter
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I got my alternator installed today and it seems to be working correctly now. I connected the wires as follows:

Thick, solid yellow wire to BAT
Solid red wire to GND
White wire to FLD

Now when the engine is shut off, the battery reads about 12.5V and when the engine is running, it reads anywhere between 14 and 15V. I'm thinking that my alternator problem is solved . Thanks for the help everyone.

I finally got the engine and transmission rebuilt!
1966 Mustang
289 c.i., 2V carb
Automatic C4 transmission
Griffin 2 core aluminum radiator
Hedman headers
Dual Flowmaster 50 Series Delta mufflers
Ultra thin Spal 14" electric fan
BoxcarJoes is offline  
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