I've got a 1991 F250 7.3L IDI and my battery light has started to come on intermittently. When the light is on, I've checked my alternator output at the battery and it is about 12.4v. Then after I wiggle the alternator wiring plug I get 13.8v at the battery. So I'm assuming this plug unit (is this called the pigtail?) is bad and I'll need to replace it. It does seem a little loose. A couple of questions:

1) Does anyone know where I can find an aftermarket replacement pigtail?
2) Is my alternator one of the 2G alternators that you hear horror stories about? And if so, should I be replacing it with a 3G? I can't figure out how to attach a photo to this post, but my alternator has the fan on the outside and has the female plug input on the top with a post also on the top that also connects to a wire from the wiring harness.

Thanks.

 

You say "post" which would mean 1G, but the 1G has no plugs.
I know that diesels used the 1G alternator for a long time.
A picture might be very helpful.
https://www.ford-trucks.com/forums/forum77/


On a 2G there are 2 plugs

1) A regulator plug with three pins (green/red, white/black and yellow/white wires)
2) An output plug with two black/orange wires that are spliced into a fusible link and the white/black stator wire. (the infamous "Fire Plug")



I'm going to assume you need the plug that fails all the time.

These pigtails can be found at almost any parts store.
Here are a few examples...

Borg-Warner PT-780
Standard Motor Products S-542
Power Plug 4628011
KEM Parts 350-220
Pico 5711
Dorman 85123
Motormite 08622
NAPA VRA400

Be sure to pack the plug full of dielectric silicone grease before you connect it.
Perhaps you can stave off the corrosion that causes these things to melt down.

 

This is a picture of the back of a 2G



It's the rectangular plug that connects on the left that has a meltdown.

 

Above are two photos of my alternator. Is this the 1G that I have? The one plug has two terminals, in a T formation 90 degrees perpendicular to each other. And then there is just the post where the other wire is attached with a nut. Thanks for your help.

 

I've never seen a 1G with a plug built into it.
it should have separate attachment points.

If it has an external regulator it's a 1G.

 

I replaced the alternator wiring pigtail and that seemed to help a little bit but now the charging system on my truck is flickering. Sometimes it charges at 13.4v or a little more and then it will drop down to no charge at all. If I push on the pigtail to make sure it is getting good contact the charge goes up to full for a bit and then it will drop out again. Is this is symptoms of a bad regulator? I've never had an alternator that flickers like this.

 

It does sound like the regulator is acting flaky, or the brushes are shot.

 

What I was putting off from the beginning - the alternator sounds like it is dying. You can have regulators replaced but the brushes may gone too so a new or refurbished alternator is likely the best route?

 

[QUOTE=borffmann;14072321]I replaced the alternator wiring pigtail and that seemed to help a little bit but now the charging system on my truck is flickering. Sometimes it charges at 13.4v or a little more and then it will drop down to no charge at all. If I push on the pigtail to make sure it is getting good contact the charge goes up to full for a bit and then it will drop out again. Is this is symptoms of a bad regulator? I've never had an alternator that flickers like this

Where did you buy pigtail?