Alternator Wiring on 250c

I replaced the alternator in my 250c today, but it's only showing 12.23v at idle, measuring at the battery. That seems low to me.

Here's a photo of how it's setup:
Red - Going to starter
Yellow - Ground (only other color wire I had)

mvphoto33040.jpg


The alternator has terminals for a field wire and stator. Someone suggested connecting the field wired to the voltage regulator, afraid mine is dead though, a new one is in the mail. Is that correct though?
 
You have a Ford automotive alternator that requires a matching external voltage regulator.

The regulator feeds controlled current into the (F)ield terminal, the one with the white insulator on in in your photo.

Get a VR for a 1979 F150, and connect it as shown. (There are some alternate ways that work, as well.)

Or get an INTERNALLY-regulated alternator.
<img src = "https://www.gondtc.com/~blweltin/Bob/SimpleFordAlternatorCircuit2.jpg">
 
Great advice from Bob.

I've seen a number of Delco conversions on Ford tractors, but never a Motorola. I guess whoever did that
wanted to keep it all Ford. Motorola alternators are every bit as reliable as a Delco, however those first
generation models require an external regulator.
 
(quoted from post at 08:30:07 03/18/19) Great advice from Bob.

I've seen a number of Delco conversions on Ford tractors, but never a Motorola. I guess whoever did that
wanted to keep it all Ford. Motorola alternators are every bit as reliable as a Delco, however those first
generation models require an external regulator.

I don't think it was a conversion. The 250C came with the Motorola alternator and external regulator from the factory.
 
Right. This is after I ordered a "replacement" online, that turned out not to fit at all. So I took the OEM alternator to Autozone to see if they could match it up, walked out with this.

Though, the OEM was not plugged into the regulator either.

So, I couldn't attach this to the original Ford v-reg?
 
I'm sorry, I mis-spoke in my last post. What I meant to say is that Ford never used a first generation
Motorola alternator on tractors. By first generation I mean the alternators that came out in 1965 in Ford
cars and trucks and were used for at least the next 10 years if not longer.
 
The alternator you show is a "1st gen" Ford automotive Motorola alternator that was never used in tractors.
The voltage regulators would not be compatible between the two if your tractor has the OEM regulator.

You can either get the right Motorola alternator to work with your existing OEM regulator, or else get a 1st
gen automotive regulator and re-wire it. Or, convert to an internally regulated Delco.
 
(quoted from post at 09:40:19 03/18/19) The alternator you show is a "1st gen" Ford automotive Motorola alternator that was never used in tractors.
The voltage regulators would not be compatible between the two if your tractor has the OEM regulator.

You can either get the right Motorola alternator to work with your existing OEM regulator, or else get a 1st
gen automotive regulator and re-wire it. Or, convert to an internally regulated Delco.
Is Motorcraft a Motorola? Says Motorcraft in picture?
 
I think I'm losing my mind - it must be Monday!! Arghhh! You're right. Motorcraft and Motorola are different.

I think I'll take about a week off. :-(
 
Ok, I’ve replaced the alternator with what I think is OEM as well as the vreg. Still now go though. What am I doing wrong?
 
(quoted from post at 12:06:35 03/22/19) ..................in addition to above, where is regulator?

Should be four photos showing that. But in case not:
Red is coming off of starter post, which is also coming with the pos on the battery.
Black clip is ground, off of engine block and the ground on the regulator
Yellow is connected to the ignition switch, going to the yellow wire on the regulator and is reading 12.14v when the engine is going.
Red clip is coming from the field wire, green, on the regulator
 
(quoted from post at 13:51:32 03/22/19) Why is the red or Orange? wire not connected to anything?

Only because I don’t know what it should go to. ;)

The red off of the regulator measures about 8v
The green field wire off the regulator measures about 4v
 
(quoted from post at 17:03:29 03/22/19)
(quoted from post at 13:51:32 03/22/19) Why is the red or Orange? wire not connected to anything?

Only because I don’t know what it should go to. ;)

The red off of the regulator measures about 8v
The green field wire off the regulator measures about 4v
believe that it should connect to idiot light and the stud terminal at about 8:30 in your picture. I say "I believe", because of the several diagrams that I have for Motorola, there are minor differences in that some alts have an additional diode, as compared to yours.
 
(quoted from post at 14:28:20 03/22/19)
(quoted from post at 17:03:29 03/22/19)
(quoted from post at 13:51:32 03/22/19) Why is the red or Orange? wire not connected to anything?

Only because I don’t know what it should go to. ;)

The red off of the regulator measures about 8v
The green field wire off the regulator measures about 4v
believe that it should connect to idiot light and the stud terminal at about 8:30 in your picture. I say "I believe", because of the several diagrams that I have for Motorola, there are minor differences in that some alts have an additional diode, as compared to yours.

I'll give it a try.

I had a real hard time finding the right alt/regulator units to use. Really just going off what the store here and Amazon says. How do you go about finding the original part numbers?

That said, these "should" be paired up right, both for a 3910 either way. It's just getting the wiring right I hope.
 
(quoted from post at 19:01:20 03/22/19)
(quoted from post at 14:28:20 03/22/19)
(quoted from post at 17:03:29 03/22/19)
(quoted from post at 13:51:32 03/22/19) Why is the red or Orange? wire not connected to anything?

Only because I don’t know what it should go to. ;)

The red off of the regulator measures about 8v
The green field wire off the regulator measures about 4v
believe that it should connect to idiot light and the stud terminal at about 8:30 in your picture. I say "I believe", because of the several diagrams that I have for Motorola, there are minor differences in that some alts have an additional diode, as compared to yours.

I'll give it a try.

I had a real hard time finding the right alt/regulator units to use. Really just going off what the store here and Amazon says. How do you go about finding the original part numbers?

That said, these "should" be paired up right, both for a 3910 either way. It's just getting the wiring right I hope.
f you go to New Holland on line parts store/catalog, you will find CNH/Ford numbers, but not the Motorola, Transpo numbers. Of little value I would say.
 
That did it. Connecting the red wire from the regulator to the reg post on the alternator made the magic happen. Was at about 13.5v running at the battery.

Finally, I’ve been working on this for months. Probably the 4th alternator I’ve tried.
 
(quoted from post at 19:32:39 03/23/19) That did it. Connecting the red wire from the regulator to the reg post on the alternator made the magic happen. Was at about 13.5v running at the battery.

Finally, I’ve been working on this for months. Probably the 4th alternator I’ve tried.
appy for you my man! :D
 

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