Ford Mustang Forum banner

1965 mustang charging system problems.

8536 Views 9 Replies 3 Participants Last post by  rex1965
hello all! i have a 1965 mustang with an inline 6 200ci. i replaced the alternator and voltage regulator about 3 or 4 years ago when i got the car. it has not been driven on the road at all so everything is basically brand new. The alt light is on and when i disconect the negative from the battery it stalls. the battery reads 12.47 all the time when running and when i rev it, the battery reads a little over 12.47 so its getting a small charge. the back of the alternator is hooked up like:

black wire/yellow tracer- to battery post on alt
white wire-white plastic ring on alt
black wire/red tracer(2 wires connected) to ground

there is one post that has nothing on it and it has a black plastic ring on it and i'm not sure what goes to it. i tried jumping the terminal at the voltage regulator and it did not chage anything. i also had one wire coming from the starter solenoid to the alt but i dont know where it goes to on the alternator or even if its a real wire for anything. any ideas or input would be great!
See less See more
1 - 10 of 10 Posts
From what your stating is the battery is charging at 12.47, there might be a contact stuck in your voltage regulator turning the ALT Light On. Check out the attached wiring diagram.
I thaught it should charge at 14v? And shouldent it still run when then the negative is disconnected? And I'm going to replace the voltage regulator in the Next day or so to mark that off the list of possibilitys.
The S wire on the voltage regulator runs to the S terminal on the alternator, the alternator S terminal supplies about 6-11 volts when the engine is running to turn the voltage regulator on. If this wire is not hooked up or has no voltage the regulator will never be turned on to start the charging system. You need to check this out. Also there is a wiring and vacuum diagrams at the top of this forum, that has the color of the wires, and that should help. Since you have 2 wires connected to the ground terminal on the alternator, see if one of them is the S wire to the regulator, and if it is, then connect it to the S term on the alternator, start the car, and see if it is charging then. Also it is not recommended to remove either of the battery post cables when the engine is running, as a high voltage spike is possible, which can damage the diodes in the alternator. Post your results. Good luck.
See less See more
The 2 wires are crimped together so they both go on the ground(they are the same color) and I don't have any wires that could possibly go on the S terminal. Should I make a wire from the alternator to the voltage regualtor just to find out if that's the problem then look in the factory's wires to see if there's any problems with them?
See less See more
Okay, this is how my 65 alternator is wired and it works,

Black with yellow stripe (2 wires) to the BAT term (black ring)
White to the FLD term (red ring)
White with black stripe to the STA term (white ring)
Black with red stripe to the ground term

The white wires look almost identical, you have to roll it over to see the stripe.

Do you have a factory AMP gauge or the indicator light, I have the indicator light? Post your results. Good Luck.
See less See more
I have indicator lights. I think I might have the wrong harness in the car. Because I only do not have the white wire with the black stripe on it.
Someone may have installed a harness for a 66, it has the S terminal on the regulator running to the ignition switch ON position it is green with a red stripe, look at the wires at the regulator for either the white with black stripe or the green with red stripe. Post your results. Good Luck.
I have a green and red wire going to the voltage regulator but is not going the the S terminal. And I was looking at the altornator wireing harness and saw that the connection part has a all white wire, thick black ad yellow wire, black and white wire. And the other side they match up except
For the middle one that has the thick black and yellow one on the altornator side and the other side has the white and black one. So I think I'm going to order the correct harness and see if it helps out.
See less See more
You could either run the green red wire from the regulator to the ignition switch ON side or to the S term on the alternator, either way, should get the charging system working. Good Luck.
1 - 10 of 10 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.