24 volt CUCV

[mtnbiker727]

Once this is all over, I'll be looking at a 1986 CUCV that will be put back up for sale. As far as I know the electrical system has not been modified, which means (I think) it's set up with 2 batteries, 2 alternators, and at least some of the components run on 24v.

I plan on using this truck as a truck to do truck things, like hauling firewood, towing trailers, etc.

I know some people have done a 12v conversion, and I haven't read how to do it, but I know it's out there.

Is the 24v stock system really a problem? Is it really worth it to rewire the truck, and (I'm assuming) buy new gauges and stuff like that?

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[Arkansas_V8]

Once this is all over, I'll be looking at a 1986 CUCV that will be put back up for sale. As far as I know the electrical system has not been modified, which means (I think) it's set up with 2 batteries, 2 alternators, and at least some of the components run on 24v.

I plan on using this truck as a truck to do truck things, like hauling firewood, towing trailers, etc.

I know some people have done a 12v conversion, and I haven't read how to do it, but I know it's out there.

Is the 24v stock system really a problem? Is it really worth it to rewire the truck, and (I'm assuming) buy new gauges and stuff like that?

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I wouldn’t bother with it until it makes you.

 

[Vbb199]

The only things I would think you'd be worried with would be trailer plugs, that use a 12v source.

 

[Frankenchevy]

The gauges will work either way

 

[SDJunkMan]

It is actually a 12/24 volt system. The 12 volt side was primilarily there to power radios and other military electronics. The starter is 24 volt but the lights, gauges, and heater are all 12 volt. Unless the original wiring has been hacked, it works fine. It does take a little more work figuring out wiring problems, but once you understand how it works its not too bad.

 

[mtnbiker727]

It is actually a 12/24 volt system. The 12 volt side was primilarily there to power radios and other military electronics. The starter is 24 volt but the lights, gauges, and heater are all 12 volt. Unless the original wiring has been hacked, it works fine. It does take a little more work figuring out wiring problems, but once you understand how it works its not too bad.

So basically, if it ain't broke, don't fix it....

That sounds like a good plan to me.

 

[SDJunkMan]

So basically, if it ain't broke, don't fix it....

That sounds like a good plan to me.

That's what I have been told. The Steel Soldiers forum is a good source for information. They have a lot of the military tech manuals availible, and alot of experienced people that are very helpful.

 

[militaryjeep]

Everything on a CUCV is 12V EXCEPT the starter and the voltage gauge on the dash. All the other gauges, lighting and controls are 12V. The Glow system is 12V but the plugs have a large resistor on the firewall to drop down the 24V to 12V.

All this was done so the truck could be slave cable started from another 24V military vehicle using the socket on the front grill.

The unique parts are the alternators, although they look like regular 60 amp units, they have an extra stud on the back that is a floating ground. The case of the alternator is not grounded to the internals like a normal alternator. This allows the ground of the second alternator to be attached to the 12V output of the first alternator thereby giving 24V to charge the system at 24V. The large terminal strip on the firewall gives access to 24V for hooking up military radios if need be without damaging the 12V circuits on the truck.
It is pretty easy to convert a truck to straight 12V by changing the starter and moving a few wires. I would not do it unless the wiring has been damaged or both alternators go bad.

 

[AuroraGirl]

Everything on a CUCV is 12V EXCEPT the starter and the voltage gauge on the dash. All the other gauges, lighting and controls are 12V. The Glow system is 12V but the plugs have a large resistor on the firewall to drop down the 24V to 12V.

All this was done so the truck could be slave cable started from another 24V military vehicle using the socket on the front grill.

The unique parts are the alternators, although they look like regular 60 amp units, they have an extra stud on the back that is a floating ground. The case of the alternator is not grounded to the internals like a normal alternator. This allows the ground of the second alternator to be attached to the 12V output of the first alternator thereby giving 24V to charge the system at 24V. The large terminal strip on the firewall gives access to 24V for hooking up military radios if need be without damaging the 12V circuits on the truck.
It is pretty easy to convert a truck to straight 12V by changing the starter and moving a few wires. I would not do it unless the wiring has been damaged or both alternators go bad.

And im sure there might be an accessory or aftermarket something out there thats 24 volt that he has a plug and play system for, if anything. I know a lot of lighting stuff can run 24 volts.

 

[HotRodPC]

It is actually a 12/24 volt system. The 12 volt side was primilarily there to power radios and other military electronics. The starter is 24 volt but the lights, gauges, and heater are all 12 volt. Unless the original wiring has been hacked, it works fine. It does take a little more work figuring out wiring problems, but once you understand how it works its not too bad.

I believe this to be the most correct and accurate answer. It's a diesel originally so even though it would NOT have been 24 volt, it's still going to have dual batteries even for the Civilian 6.2 trucks. But to the best of my knowledge as stated, the truck chassis itself is all 12 volt all the military added components like plugs and IIRC the black out lights are 24 volt. It's not like the taillights, and standard headlights need 24 volt bulbs since they actually run on 12 volt just like a civilian truck does.

 

[ballencd]

The alternators each charge one battery on these trucks....M1008, M1009....etc. The ambulance version is a bit different I think..?
I drove an M1009 for 18 years and kept the 12/24 volt system intact. The starter as previously stated used the 24V and so did the glow plug circuit. The resistors dropped the 24V to 12V for the glow plugs though. The rest of the vehicle used only 12V. There is a ton of info on this system on the Steel Soldiers site and the guys there are mostly very helpful when asking questions but do your research first and show pictures. The system is very reliable and not that hard to figure out once you get the general gist of what is happening. It has been awhile since I have worked on one of these vehicles but it seems only one of the alternators had a floating ground so it could charge the second battery isolated from the first battery. I want to say the alternators were the same other then only one had an isolated ground so you had to be careful which one went in which position. That could have been a wrong part (no isolated ground alternator) installed at some time before I got the vehicle so I don't know about that. It would work in one position but not the other. If two non isolated ground alternators were installed it would cause a direct short and toast a battery pretty quick along with some wiring! : (

 

[SDJunkMan]

it seems only one of the alternators had a floating ground so it could charge the second battery isolated from the first battery. (

When the trucks were new both alternators were isolated ground, but the truck only requires one on the left (drivers) side. When the left alternator crapped out, it was easy to swap the isolated ground alternator from the right side, and put a normal non isolated ground alternator back in the right spot. There is a thread on Steel Soldiers that tells how to convert a non isolated ground alternator to an isolated ground.