GI 60 AMP alternator wiring problem

Deadguy · Post by **Deadguy** » Wed Apr 11, 2012 10:56 pm

Id that something is backfeeding in the wiring. I turn the vehicle on, it runs nice and healthy, but the ignition wires get hot. I then try and turn it off, and it won't turn off unless I choke it out.
I'm trying to isolate the problem. There is one wire coming out of the generator that is getting hot. This is it, if anyone has any suggestions, I'm all ears!

Post by **wesk** » Wed Apr 11, 2012 11:23 pm

Disconnect the cable assembly from the regulator to the generator. Start the engine and then try to shut it down. Does the problem still persist?

Deadguy · Post by **Deadguy** » Thu Apr 12, 2012 1:06 am

I don't think I have a voltage regulator. I have an oversize generator, the guy who sold me the vehicle says it was probably a radio jeep at one point. I remember trying to work it out with John from Midwest Military on the phone, and couldn't find one.
I don't have a lift. The guys at the local jeep shop pulled the engine, and sent it off to the rebuilder. The guy who pulled the engine is no longer there, and another guy hooked it back up. It didn't have the problem before the engine was pulled, and the only rewiring i did as far as the engine goes, is at the keyed ignition switch. I listened to Wes and swapped out the old switch with one rated for 24 volts.

danrothe2001 · Post by **danrothe2001** » Thu Apr 12, 2012 5:22 am

There has to be a regulator somewhere, whether it is internal in the generator or external. The one wire 12 volt alternators with an internal regulator are notorious for backfeeding and require a diode on the trigger wire. However, with the wires getting hot it sounds like excessive resistance somewhere like a bad ground. Eletricity will find ground. whether it is the right path or the wrong one. Taking the long way round usually powers up something that shouldn't. I can't tell you specifics as I am still new to jeeps, but definately make sure that the engine and generator are grounded to the frame.

Dan

Post by **wesk** » Thu Apr 12, 2012 9:42 am

Resistance is a separate issue from back feeding.

You have a 60 amp GI alternator with built in regulator. Remove the two wires from the alternator and run the engine. If they are semi-permanently installed on the alternator then disconnect them at their other end. The large wire generally is connected to the starter battery terminal and the small wire is usually fed to the ignition switch via wire 11.

If the problem is gone fix the regulator inside the alternator.

jonesal · Post by **jonesal** » Tue Apr 17, 2012 10:38 am

Wes has good advice. I've overhauled a few of these for M35s and the regulator can be finicky if the overall system (esp. wiring harness) is not functioning properly. One word of caution. If you have +24V to the small wire (activates the regulator), make sure you have batteries hooked up or you can smoke the regulator. I've seen several catch fire so the hot wire should be of particular concern. Get the part number off the generator tag to match the proper internal regulator for particular vendor if that is the problem (follow Wes' procedure). Lots of info on the internet - I can email you the TM for generator if I know the model number (or NSN) if they are not on this website. The TMs call it a generator whether its Prestolite, Leece-Neville, etc. so be aware of that. The output voltage is also adjustable under the hex head plug to get exact output. Your main wire looks precarious (is that shrink wrap over the bare wire?) - the smaller wire should have a rubber connector on a 6-or-so-inch pigtail. When I put this generator on my test stand and run it wide open it will stall the test stand so these can put out way more than 100 amps. Maybe that's a second word of caution for that wire.

Good luck - they are great units.

Al Jones

Deadguy · Post by **Deadguy** » Tue Apr 17, 2012 12:27 pm

I have my vehicle at a jeep custom shop. My last engine threw a bearing. They pulled it, it went back to the rebuilder, and by the time it got back, they had fired the guy that pulled the engine. A new guy hooked it up. No problem before the engine was pulled. While it was gone, I installed turn signals and a cab heater, and replaced that little spider harness for the gauges. I didn't really do much else. I'm thinking that either the regulator gave out right around when they pulled the engine, or maybe they hooked it back up wrong, at least initially. The engine runs, I just can't turn it off without choking it out. I'll test more, but I'm out of town until Monday night.

Deadguy · Post by **Deadguy** » Wed Apr 25, 2012 11:56 pm

Alright, pulled that one wire, and now it runs really heartily, charges great, the wires don't get hot, and it turns off fine. Does anyone know what that wire goes to? It might not even have been installed on the original generator, like I said, the guy who pulled my engine is not the same guy that put it back in.

This is it without the finger

Oh, and it's late and I'm home right now, but I think it goes back to the ignition switch.

Post by **wesk** » Fri Apr 27, 2012 12:06 am

There are three wires in your first photo above. The one you are pointing at we cannot see how it is connected to the alternator since your hand is in the way. Also can you tell us where the other end of that wire goes?

The other large wire on that alternator goes to the starter switch terminal. The small wire goes to your ignition switch.

jonesal · Post by **jonesal** » Fri Apr 27, 2012 6:51 am

Of the three wires shown in your photo, for your application, you only need two wires. Attached is a pdf of the Prestolite wiring diagram. Your third wire, the "R" lead, should not be hooked up. Also, you are missing your ground wire, again see the wiring diagram. This generator is not grounded through the case - a mistake with this unit that can over stress the regulator and fry it (corrosion at the mounts, etc.).

Well that's embarrassing, I can't figure out how to attach a file. Check your email. I'll edit this and try and post the pdf later.

Al[/img]

Deadguy · Post by **Deadguy** » Fri Apr 27, 2012 9:59 am

So, the spot that was hooked up to the ignition, should not be hooked up? Where should the ground wire be?

Post by **wesk** » Fri Apr 27, 2012 11:12 am

Dan,

I want to help you out but I can't if you do not answer my questions.

My questions for you I stated above are:

The wire under your finger in your first photo. Is it the wire you disconnected? If it is what exactly was it connected too on each end? Your hand covers the connecting point on the alternator.

As I have said above, in your second photo, the small wire has to go to the ignition switch and the large wire to the starter's battery terminal.

There aren't a lot of choices for locating a ground wire on that alternator. The easiest is to use a longer threaded bolt on the alternator at the adjusting bracket and after tightening the adjustment bolt then add the ground wire, a star washer and nut to the rear side of the bolt.

Deadguy · Post by **Deadguy** » Fri Apr 27, 2012 5:52 pm

I got this message after I'm home and my vehicle is locked up in the shop for the weekend. The wire I was pointing too is absent in the second photo. The bare terminal with the red arrow pointed at it held the wire. Pulling that wire made everything fire up and run great. I will check on Monday, but I believe I have that wire going to the "on" position on the ignition switch. Which means it is now just a live "loose" wire and I should probably remove it. I haven't gone over the alternator carefully to check for a ground. It must have has a ground when I first got it back in June. It's running great now, which would seem to indicate to me that a ground is in place, but I'll go over it carefully on Monday. I didn't swap the engine back in, so I'm not sure, and the guy who did is also out until monday.

Deadguy · Post by **Deadguy** » Tue May 01, 2012 5:45 pm

Alright, got back into the shop today. It took me a little while-friday I was hit by a car on my bike, in a coma for four hours, and had road rash and head, back, and leg stitches, and brain bleeding. Cops are surprised I'm even still alive.
The wire that I disconnected, the one pointed out by the finger, and then the terminal (with no wire on it) is pointed out by the red arrow, apparently led straight back to the ignition switch. With it gone, the vehicle runs great. The only thing I am worried about now, is the ground. Wes, I see the grounded brace spot you point out, but am I supposed to have some separate lead running there? As it is right now, I took it around the block, and it is running strong.