Exciter Wire Question

[AZDeuce]

Gentlemen:

My M1009 has been down for over 3 months now due to electrical problems. It's kicking my butt, which isn't too hard as I'm an electric system moron.

I've ran off all kinds of information and links off this site, as well as the electric portion of the manual, of course I forgot the scematics! (Not that I could read them anyway). I've learned a lot, rebuilt both alternators, replaced all the fusible links coming off the Engine Harness Block (EHB) on the firewall.

Currently I have the complete dash out of her, due to searching for the starter relays. APPARENTLY my starter relays got removed when the Sheriif Dept added A/C, and a radio to this beast.

The last time I thought I'd fixed this truck about a month ago, I had 14.5 on Btry and alt #1, which I had rebuilt, and 14.9 at Btry 2 and 27.? at Alt #2, which I did NOT rebuild. I knew #2 was a little high, but didn't think it was too bad, so I took it for a drive I got 2 blocks from the house when I smelled something electrical, and both Alt 1 & 2 lights came on.......DOH!

So I parked her and decided to rebuild #2 Alt. I got it installed today, and got good readings all around, both at the Alt and btrys, for both 1 & 2, with the key off.

So I turned the key on to get a reading on both of the exciter wires, both are dead.

So my question is where do the exciter wires get their power from so I can check there first?.

THANKS for any, and all help.

 

[AZDeuce]

Nobody knows? Or, is everybody out of town for weekend......or worse, snowed in?

 

[dependable]

Gen 1 exciter circiut gets power from heater blower fuse (top of the fuse box). Gen 2 circuit gets power from the 24v fuse ( a regular fuse near bottom of fuse box). Since you'll be hanging out under the dash, make there is a small black wire attached to cab above the parking brake. This is the ground for 24 v part of dash wireing.

 

[AZDeuce]

Dependable:

Thanks for that info! That'll give me a place to start looking.

 

[Warthog]

The black ground wire at the emergency brake is used for many items in the dash, Seatbelts buzzer and lights, dash lights, Injector pump power shutoff, and more. Not just the 24v stuff.

Here is the wiring diagram for the alternators.

 

[AZDeuce]

Ok, THANKS for the help so far.

I just went out and turned on the key, and the heater blower......NO blower. So I pulled the fuse, and it appeared fine, I checked the contacts and got 11.9V (the btrys are getting low - and I have no charger) I installed a NEW fuse.

I did the same at the 24V fuse, and got 24.5 at the fuse box connetions, I installed a NEW fuse even though there was nothing wrong with the old one.

I then did a voltage check on the exciter wire at both Alts, with the key ON, but got NOTHING!

So I saw the two brown wires coming out of the fuse box at the fire wall, under the master cylinder, I peeled back some plastic for a reading on both wires (with the key ON) and got NO voltage......what am I missing?

I got power at the box on both fuse contacts, and new fuses, what am I not seeing?

I am assuming it must be something physical/mechancal at this point, a bad connection of some sort.

Is it possible to disconnect the wiring harness on the engine side of the fuse box, and somehow remove the fuse box for a "lookie-see?"

I'm not electrically savy enough to know how to check it any further except to get the fuse box out of there, and look for a bad/melted or otherwise damaged connection.

Any ideas?

"Dazed and confused in Buckeye"

 

[AZDeuce]

UPDATE: 02-07-11, 1700 Hrs.

OK.......I think I found the problem.

I had power coming into the fuse box for both exciter wires, but nothing coming out and going to the alternator side of the exciter wires.

So I figured the problem must lie in the fuse box some where. I noticed a screw head sticking out of the center of the mass of wires that feeds into the back of the fuse box from the engine compartment, so I unscrewed it, and was able to pull what essentially is a giant plug out of the fuse box.

The inside of the plug is full of male ends, that match up with the female ends in the fuse box. But what a disaster area, the plug had melted, most of the connections were covered in plastic, or got so hot that they melted!!

The back of the fuse box looks similar...yet ALL of my fuses are still servicable.......how in the world does that happen?

Anyway, I'll need a take out, or new fuse box, and that plug and all of the connectors.

Is anybody parting out a CUCV? I think for me, the easiest way to do this would be to get a take out fuse box, and have the wires cut off about 6" behind the plug, so I can graft them to my original engine harness. and maybe do the same thing to the wires going into the fuse box so I can just cut them out and reattach them when I reattach the box.

Anyway that's where I'm at, the trucks still down, but at least I think I found the problem.

 

[Barrman]

It probably wasn't melted. GM put some kind of tar/goo/di electric grease in there. They all have the black goo inside them.

If you look at the wiring drawings in appendix F of the -20. You will see that plug and what pin goes to what. I have used just that plug and some hot wires to start GM trucks before. So, yes you can do a continuity check between that plug and the plugs on the alternators.

 

[AZDeuce]

Barrman

I thought the black stuff might be some type of grease, but I still got two melted connectors. Something definitely went wrong in there.

 

[Warthog]

Barrman

I thought the black stuff might be some type of grease, but I still got two melted connectors. Something definitely went wrong in there.

Can you post a picture of the bad connectors or which wires they are?

It will help diagnosing what went wrong.

P.S. The engine compartment harness has a few wires cut. The wiper motor wires are about 6" long and both alternator wires are cut. The rest looks like it is all there.

 

[AZDeuce]

No sorry, I am technically deficient, and don't have a way to post up pictures, with my dial up webtv.

Do you have the fuse block, and it's wires too? I need everything on both sides of the fire wall, I don't care if I get the whole wiring system under the dash or not, I plan on splicing the new box into my wire harness anyway.

You can PM me with a price if you don't want to post it here.

THANKS!

 

[AZDeuce]

UPDATE 03-20-11 Exciter Wire Question

When I last reported in about a month ago, my fusebox had 4 melted contact points. Thanks to HAWKMAN, 2deuce and Warthog, I got an extra fusebox and engine harness plug, and was going to slice and dice all the wires.

But I soon found out I was in way over my ability, as several of the wires were the same size and color, but running to different locations inside the fusebox. That's the kind of thing I could screw up, so I came up with a Plan B.

I decided to break the fuse box open and cut the four wires that were attached to the melted connectors, add about a foot of wire to each one, and run them through the firewall next to the fusebox. I used the same color wires out of one of the extra harnesses.......so there wouldn't be any mistakes.

I then added in-line fuses to each wire, and tied them directly into the engine harness, bypassing the plug, and removing the need to splice and dice the rest of the fusebox wires which were fine.

This worked and I got power to my exciter wires.......WOO-HOO! When I started the truck last week neither altrnators were putting out power, I must have fried them with all the minor shorts I had during this ordeal.

So I ordered two MORE complete rebuild kits, from Spring Hill, last Sunday, and rebuilt both alternators last night.

This morning I installed them, then ran a multi-meter prestart function test and all was fine, so I fired up the Bazer, and had 14.5V at btry 1, but only 12.2V at btry 2.

WHAT in the WORLD!!??

So I pulled Alt2 which is a PITA on my truck due to the aftermarket A/C, I took it to AutoZone, and it tested BAD! I don't know how that could be as I rebuilt it last night, and was carefully watching when I hooked up the batteries for any spark or arc......and there was NONE!

So I take alt 2 back home, and I had one rebuild kit left, so I installed it, hooked it all back up, re-connected the batteries, (no sparks), started her up and #1 alt/btry was fine but still no joy on #2 I had 12.3V at btry 2 and 26.3V on the big wire at Alt 2.

I am at a loss, what's wrong, and what am I missing?

HELP!!!

 

[mistaken1]

I am assuming you did not replace all of the windings in alternator #2. It may need to be completely rebuilt by an alternator rebuild shop.

 

[stampy]

You know that the alternators on the cucv are not the same type right? One has an isolated ground, The other doesn't as they are both 12v alternators. Are all of your gen lights on? a blown bulb can disable the exciter wire( I think)

 

[AZDeuce]

Mistaken1

No I did not, maybe I should take it to a shop. I only changed the bolt in internal parts.

Stampy

Yes both of mine are isolated ground types #1 works, #2 doesn't after rebuilding them both last night, and #2 again today.

Exciter wires both work now sinse by-passing the fusebox.

I'm going to agree with Mistaken1, except that Alt 2 is brand new (of course that doesn't mean it isn't bad). I got distraced, and broke the original case while installing new bearings (DOH!), I bought a 85 Cadillac alt took it home, and took it apart, and put the isolated ground parts in out of the broken alt, and was doing ok until I realized the rectifier bolt that protudes through the case for a ground wire on Alt1 or a hot wire on Alt 2 wouldn't work as there was NO HOLE for it to protude through the case.

So....I drilled the hole, and everything went together fine, being a new 100Amp Alt, I didn't change any parts, all I did was add the isloted ground washers and wire.

When I hooked up the negative battery cable I got a arc that would make a Miller Welder proud.obviously I missed something so out came #2......AGAIN!

I opened up the case and compared it to my broken case, finally I saw two metal protusions that were cast into the new case that were not present on my old case, they were touching the rectifier, and negated all my isolation parts swapping. So I took it apart, took the case to work, and got one of the machinists to remove the offending castings, and gave him the broken case as a guide.

Once that was taken care of, I installed new parts last night and when I installed it this morning I CAREFULLY installed the negative battery cable, and there was no arc, no spark nothing, it went together just fine...except it doesn't work.

At this point I'm tempted to take #1 off and put it in #2's spot, then just go get a civilian alternator for #1, trouble is I looked at the replacment alt at AutoZone, and they don't have the hole in the case for the ground wire either.

I guess I could just hook a ground wire to one of the 4 bolts that hold the case together,, or drill the hole (and remove the metal castings like I did above, and just run the civilian one in the #1 position, as that one does not need an isolated ground.

The problem is I'm "scared," I hate to take my working isolated ground alt off of #1 spot, and install it on the #2 spot, and watch it not work either. But I guess that's one way to find out (the HARD way) if Alt #2 is the problem or if there is an other issue.

 

[AZDeuce]

Hey........I just had a thought, I still have the armmeter and winding from my original Alt 2 that I broke the case on.

I'm wondering if it was possible to damage the armmeter or winding on my current alt 2 when I got the arc mentioned in my last post when I hooked up the battery, as I did it several times as I refused to believe I assembled the isolated ground wrong.

And of course I didn't do it wrong, I just failed to see the two new castings that touched the rectifier, but the point is I ARC'd it several times.

So do you think I damaged the armmeter or windings?

 

[mistaken1]

You know that the alternators on the cucv are not the same type right? One has an isolated ground, The other doesn't as they are both 12v alternators. Are all of your gen lights on? a blown bulb can disable the exciter wire( I think)

On a stock military CUCV both alternators are isolated ground units.

It is true that you can put a non-isolated ground on the drivers side but the original military units were all isolated ground.

 

[mistaken1]

Hey........I just had a thought, I still have the armmeter and winding from my original Alt 2 that I broke the case on.

I'm wondering if it was possible to damage the armmeter or winding on my current alt 2 when I got the arc mentioned in my last post when I hooked up the battery, as I did it several times as I refused to believe I assembled the isolated ground wrong.

And of course I didn't do it wrong, I just failed to see the two new castings that touched the rectifier, but the point is I ARC'd it several times.

So do you think I damaged the armmeter or windings?

Yes an arc that big could have damage other parts inside Alt #2.

Take it to a shop to have it tested or if you believe your original isolated ground internals (the one that had the broken case) are good then swap them into your good (newly modified) case with that second rebuild kit parts (not the rebuild kit from the welding incident) and see what you get.

 

[AZDeuce]

Mistaken1

Cool! Hopefully tomorrows project if I can fit it in.

 

[stampy]

Thanks mistaken1 I did not know that. I assumed as I had seen many with a plain alt on 1 and a isolated ground on 2 that's the way they were.