'86 m1009 with TOO much power possible bad ground?

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DDT

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Just fininshed my second banks turbo install on a m1009. First had dual batteries with 1 alternator no problem. My m1009 has the dual Batteries and Dual alternators. I had to remove the passengerside grounds from the frame near the lower radiator hose. (heat + will rub)

I have a good ground off of the valve cover stud so can I ground the pass alt there? I tried it and hooked up the batteries and a little sizzle (2-3 sec). So the power is running to the driver side alt wire along the firewall it got warm, not burnt but warm. I printed the circuits from CUCV Electrical and will redo the grounds for the alternators. Any ideas?
 

cpf240

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Someone will correct me if I'm wrong, but if the M1009 still has the stock wiring configuration for the 12v / 24v systems, then the passenger-side alt MUST be isolated from ground!
 

DDT

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Ok should I ground the passenger alt to the frame or the ground above the headlight. Also can I use the ground stud on the alternator or should I ground out to the case of the alt? Thanks all I have left on the truck is to bleed the fuel lines and I'm ready for the open road
 

Warthog

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If your truck wiring is still stock and you ground the passenger alternator ground stud to the engine, something will fry or the wiring has been modified.

Search "isolated ground" for the reasons why.
 

DDT

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The positive wiring for both alts are stock. I moved the grounds for the alts due to the banks turbo install. I have the passenger alt grounded to the valve cover stud which is grounded off the ground bank on the firewall. I think the single alt setup was grounded above passenger headlight. I'll try to regound the pass alt to the frame above the right head light next
 

Warthog

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The passenger alternator does not have a ground! It uses the 12v from the drivers alternator and front battery to feed the passenger ground stud.

This is how the two 12v alternators create the 24v electrical system.

So do not attach a ground wire to the passenger alternator.


You have already fried one of the fusible links when you heard the "sizzle"
 
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DDT

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That's it! I grounded it. I'll check continuity at the fuse able link. Are they blue and orange wires located just below the junction boxes? Thanks to all that applied ill get back one the truck this weekend looks like that's the start of the issue
 

Warthog

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Check the blue fusible link at the 12v ENG WRG HARNESS BLOCK near the master cylinder. It is te diamond shaped terminal block. You are looking for the blue link connected to the RED wire with white stripe. It feeds 12v from the front battery to the "isolated ground" terminal on the passenger alternator.

The passenger alternator is a 12v unit but when you "feed" 12v to the negative terminal it will output 24v.
 

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DDT

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I printed a circut chart from CUCV Electrical, I removed the ground I supplied to the passenger alt also.

I checked the fuse links links and so far they are ok. I checked the drivers alt set up: 1 red at positive post, small pen tip style post pluged into harness (brown), and ground wire to lower valve cover.

I have a thin black w/ white strip wire left over as it was not on the printout. Seems to be a ground wire as well.

next i rechecked the passenger alt: main red wire at pos post, red w/ white at 2nd post, small pen tip style post left bare as no wire exists on that side to plug into it. On the back of the alt it has a tube resistor which I am assuming is the isolated ground I've been hearing about.

So I attached the batteries and for 5 sec everything was good then the pass alt connection of red w/ white started to smoke. very low sizzle this time, batteries are still at 12.6v. Starting to think about switching to a single alt for the time being. Until I can make it to a meet and see another setup.

I have a extra wire soild Orange left over from the harness, which runs to positive power bank on firewall.

I never saw this one run thats why I got a deal on it plus it had a blown head gasket. It was a Navy communications vehicle which I don't know if that means it had a few extra wires under the hood.
 

rickf

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The small terminals you are talking about are tachometer connections and do not apply on your vehicle. You NEED to get the correct wiring diagram for the CUCV and follow it to a T. Do NOT, NOT, NOT hook up the batteries as a test! That can get real expensive if you set the whole harness on fire and yes it can happen, quickly. If you are not sure of the connections or of your capabilities I suggest you take it somewhere. Once you let the magic smoke out it is impossible to get it back in. I am not trying to be an azz here but you have gotten lucky once, maybe twice, third time may not be a charm.

Little hint here, 12 volt shorts make a spark, 24 volt shorts make an ARC!

Rick
 

DDT

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Thanks I may have to go to one alt setup that worked before without a hitch. Plus I can always retry to dual alts down the road thanks to all that replied
 

rickf

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If you go to one alternator then you are going to be converting to 12 volt and there are a couple of wiring changes that will have to be made. You can not run a single 24 volt alternator on this vehicle due to the fact that most of the vehicle functions are 12 volt.

Rick
 

DDT

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I rebuilt a buddys m1009 for the banks turbo install. He had the dual battery single alt setup. I thought I could recreate his loom if need be as his runs great. It has the same 24v starter and glow plugs so at this point I am leaning towards that if I cant nail this system down. I'd love to keep the dual setup but I don't know if it worked before I got it. It seems that the problem is in the grounds still so I haven't given up yet. I'll post some Picts soon. All of the pos and neg junction box connections were loose not off but loose as to 2 or 3 threads only. Maybe I'll start by taking a picture of the power strips first. I do have a small braided line 1.5" long with a small resistor orange in color attached like a flag joining the pos and neg strips.

Again I'll try a picture, thanks for the quick and direct responses
 
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rickf

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You are saying he had a single 24 volt alternator? That would work for a while but you will be buying a lot of batteries due to battery imbalance. The only thing 24 volt on those trucks is the starter. The glow plugs are actually 12 volt powered through the resistor bank on the firewall which has 24 volt feeding it. Great system as long as you don't lose one or two glow plugs. If you do then the rest are usually toast. On 1009 there is a 24 volt feed to the rear for the radio setup but the vehicle itself is entirely 12 volt. If you run a 24 volt alternator then you are charging both batteries together in series but drawing from only one for 95% of the vehicle needs. With the dual system you are charging the one battery with 12 volts and the the other alternator is charging the series with 24 volt BUT it is using the 12 volts from battery #1 as the ground so is is actually only putting out 12 volts but added on top of the 12 volt ground. That way it is all balanced. I know.............I had a hard time figuring it all out in the beginning and I am a master mechanic who specialized in electrical. I would love to meet the guy that designed this system, first I would shake his hand then I would punch him in the face!:grin:


Rick
 

DDT

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Wow great post. He has a 100 amp alt and a dual battery setup. That's as much as I know because when I rebuilt the engine he bought a new smaller starter the engine barley turned over. Not usually a good feeling when first starting a fresh rebuild. I couldnt even bleed the fuel lines. A stroke of intelligence hit me and I reinstalled the old 40 lb starter and it fired off the first crank after the feul was bled.
So I'm treating this wiring issue the same way. That it's simple once I figure it out and I'll know it like the back of my hand from then on
 

DDT

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Wow great post. He has a 100 amp alt and a dual battery setup. That's as much as I know because when I rebuilt the engine he bought a new smaller starter the engine barley turned over. Not usually a good feeling when first starting a fresh rebuild. I couldnt even bleed the fuel lines. A stroke of intelligence hit me and I reinstalled the old 40 lb starter and it fired off the first crank after the feul was bled.
So I'm treating this wiring issue the same way. That it's simple once I figure it out and I'll know it like the back of my hand from then on
 

cpf240

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Wow great post. He has a 100 amp alt and a dual battery setup. That's as much as I know because when I rebuilt the engine he bought a new smaller starter the engine barley turned over. Not usually a good feeling when first starting a fresh rebuild. I couldnt even bleed the fuel lines. A stroke of intelligence hit me and I reinstalled the old 40 lb starter and it fired off the first crank after the feul was bled.
So I'm treating this wiring issue the same way. That it's simple once I figure it out and I'll know it like the back of my hand from then on
Perhaps he was running dual batts in a 12v converted truck? That is not all that uncommon, and will charge off one alternator as well.
 

rickf

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Perhaps he was running dual batts in a 12v converted truck? That is not all that uncommon, and will charge off one alternator as well.
He said it had the same 24 volt starter and glow plugs, Problem here is the CUCV has 12 volt glows.

Mine is converted to 12 volt, less stuff to deal with and if I need a starter on the road it is easier to find. I can also get a jump if need be. The problem I have is the single alternator belt charging 100 amps into two batteries. Keep several belts, a 15 MM wrench and a big screwdriver in the truck.

Rick
 

DDT

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Eureka Eureka! I have 24.5 v at the passegner alt. It needed a 2nd ground to the manifold, I rebuilt the pass alt with new hardware and replaced the stud for the red/wht wire connection. I have almost no voltage drops around the engine with the grounds and their connection. Tomorrow I'll bleed the lines and hopefully we will be blowning smoke by noon! Thanks for those who posted picts and constructive advice earlier I was open to any ideas. Hope to see you out on the open road....

-Taylor
 
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