Need help with Alternator Wiring

[sidstang 10]

Hi,

I have a 69 Mustang Coupe with a 302 engine. I got extra parts from different cars when I bought it and I'm not sure how this should be hooked up. I have 3 wires coming off the alt. 1st is a thick black wire that comes off the alt and goes to the front headlight harness and then there's an orange one that I think goes to the field on the box on the firewall. And another wire-white or yellow, goes from the alt and it winds in through the wire harness through a rubber wire holder and goes to a ground. It doesn't connect into the harness. When I hooked them up and fired the engine the wire that goes to ground totally melted and burned off. Does anyone have pics of their wiring or can telll me how the wires are supposed to be hooked up? I have no tach on the dash. Is it possible that the wire that burned wasn't supposed to go to ground? And maybe was supposed to be for tach? 

Thank you for your help!

Sid

[magician 13]

If no one chimes in I'll get my wiring diagram tonite and see if I can help

[Wycked69 20]

See if any of the attached helps. Since your car was not wired or equipped with a factory tach, you will only have 3 wires coming off the alternator.

 

FIELD > which runs through the 3-pin connector of the wiring harness over to your voltage regulator to the "F" terminal

BATTERY> which also runs through the 3-pin connector of the alternator harness and connects to the +side (battery side) of the starter solenoid on the fender apron.

GND > This is ground and will also run through the 3-pin connector

[Midlife 814]

SidStang:

What you're describing is the alternator to headlight harness plug for a non-tach dash.  That plug is a three pin affair that routes as follows:

Black/red is ground

orange is VR signal and goes to voltage regulator

Black is main power and goes to alternator and battery solenoid connector.

 

Now then...the tach plug is a four pin affair:

black/red is ground

white/black goes to voltage regulator

orange goes to voltage regulator

black is main power and goes to alternator and battery solenoid connector

 

In both cases, there's a yellow wire on the voltage regulator that is also tied to the main power.  The tach harness has a four pin voltage regulator; the standard harness has a three pin voltage regulator.

[sidstang 10]

Thanks for your replies. The yellow wire was connected to the ground. The pin plug was missing on my wire harness and the setup to the alt has 3 holes- 2 on top and one on the bottom. The yellow wire burned completely and so I cut it off. I started the engine and it ran fine and the alt gauge was working fine. So I guess it's ok the way it's setup now. If anyone has any input, please reply.

Thanks!

[Midlife 814]

That yellow wire needs to go to the voltage regulator...

[sidstang 10]

That yellow wire needs to go to the voltage regulator...

Thank you for your help, Midlife. I got caught up in another problem with interior colors, so have put this issue aside. I will take a look at it tonight again and see what I can do to hook this up the right way. I may be missing the ground wire......

[pa69mach1 0]

All very useful info, thanks. a quick 2 questions.....non tach, using the pictured harness, what connects to "stator" pin? and.. assume the black red near end of under hood harness with ring terminal is the other side for ground by tying to fender apron near regulator?

[Mach1 Driver 560]

There is no stator connection if you don't have a tach. In the non-tach version they added an ammeter and oil gauge, and deleted the tach an alternator warning light:

 

Below is the tach version that uses a warning light to tell if its charging instead of an ammeter- when they added the tach there wasn't room for the ammeter and oil pressure gauges, so they just used a light to tell if it was charging (and added a low oil pressure light also). The alternator warning light actually works better than the ammeter which hardly ever shows anything:

[pa69mach1 0]

Ty Mach 1 Driver! so on backside alternator there is a pin/ terminal labeled "STA" for the Stator wire. What would you suggest to address it.... just leave bare/ unprotected or something else?

[Mach1 Driver 560]

There are plugs that pop into the holes to cover the nuts- not shown here, but mentioned:

[pa69mach1 0]

Yes understood, TY for your responding to this!! obviously I dont know much about alternators but the repo harness connection like pictured about thread by wycked 69 doesnt have stat cradle for a plug cover....only "flo" and "battery" cradles (again this is a non tach car but replacing what looks to be original harness that was made for with tach similiar to your last post picture) and Im not sure what the stat terminal puts out if anything so therefore does it need somehow covered since not being used.

By the way the schemetic you sent earlier... its great, what is your source as I have the Osborn and Drake versions that arent nearly as specific, ledgeable.

[Mach1 Driver 560]

3 hours ago, pa69mach1 said:

By the way the schemetic you sent earlier... its great, what is your source as I have the Osborn and Drake versions that arent nearly as specific, ledgeable.

I saw the need and made the documents- I'm an electrical engineer. You may be interested in the alternator document or others I put on Google Drive for anyone to download:

https://drive.google.com/drive/folders/10FqYlsGT1XXr8B5TCF9WAASkU4vdPtuJ?usp=sharing

Most forums don't allow uploading of large files, so I parked several useful documents on Google Drive. Using the link above, you have free access to all the documents in this directory.

[Mach1 Driver 560]

To further answer your question, the stator is not protected by anything on my alternator (non-tach car), but it is hot, and has a rather nasty little sawtooth wave that is around 7v. This terminal is also used to power an electric choke when an aftermarket Holley carburetor is added.

 

[pa69mach1 0]

Thank you again so much for your help! Hoping others can use all this useful info as well.