12 or 24 VOLT How do i know?

[radbaddad]

So i picked up an 85 cucv m1008 a while back and havent really had any time to look at it. The truck has been sitting for 15yrs literally! Not run! First order of biz was to see if it would even turn. I noticed straight away that someone had installed new batteries in 2005 2006. They were wired 12volt parallel + to + and - to -. I picked up some brand new (series 27) batteries and tried wiring both ways. Only would get a starter click either or. I figured its locked or starter is bad. Managed to turn over a little with breaker so moved on to starter. Noticed the starter has been replaced. While rusty it definitely does not have the same patina as the rest of the undercarriage / block and new looking bolts. Took the starter down and discovered that there was no positive hooked to the starter. Only the tickler. Which explains just the click. Hooked a fairly heavy (#4) wire that i found in the bed to starter and tried again. Just a click on 12. Cranked for about 15 seconds on 24 before it started to melt down the start wire. I also found a piece of wire in the bed also #4 that seemed to have an end melted off. Possibly from when someone tried 15yrs ago.

Now that you have the background info my questions are.

1. How do I tell if the starter is 12 or 24 volt?
2. How do i tell if the truck has been rewired to 12 volt?
3. Should i just change it to 12 volt?
4. Would i be better off just slapping in the 350 that i have sitting around that i know runs and drives?

Thanks In advance!
I will now pour a tall glass of Titos and tea while I wait for replies.

 

[radbaddad]

Anyone?

 

[richingalveston]

are both alternators hooked up. if it was converted to 12 volt then one alt will probably be disconnected. does the wiring harness look like it has been butchered. are there any markings on the starter.
If the cables were set up to be in parallel then it was probably converted to 12.
The motors are fairly simple, I would see if you can fix what you have before doing a motor swap. but most likely it will need some work before it will run, probably needs the fuel system gone through and a good checkout of the injection pump.

 

[richingalveston]

look up the Roscommon 12 volt conversion (on this site) and see if this has been done, it is a popular way to convert it to 12 volt.

IF the wiring harness does not appear to be butchered it may be easiest to make it stock since the wiring diagrams for this are located on this site at the top of the cucv thread (the stickies)

Also look up the doghead modification. If it has not been done, then it is good idea to do this for starters.

 

[radbaddad]

are both alternators hooked up. if it was converted to 12 volt then one alt will probably be disconnected. does the wiring harness look like it has been butchered. are there any markings on the starter.
If the cables were set up to be in parallel then it was probably converted to 12.
The motors are fairly simple, I would see if you can fix what you have before doing a motor swap. but most likely it will need some work before it will run, probably needs the fuel system gone through and a good checkout of the injection pump.

Thanks Richingalveston. Both Alts are still hooked up. The only evidence of wire tampering is someone hooked the glow plugs to a new solenoid. I feel like the batts were hooked parallel accidentally. It will not crank on 12 will on 24 but tries to catch fire. lol The starter to me looks like every other chivvy starter I've ever seen. I would like the extra HP from gas but would also like to try the 6.2.

 

[cucvrus]

Hey how about some pictures. And the starter solenoid should be marked 12 V or 24 V. Show a picture of the starter.

 

[cucvrus]

Does the starter engagement occur as soon as you hook up the batteries? The front battery should be positive cable and connect to rear negative battery. From that negative post a lighter 10 gauge wire will run to the 12 Volt power post near the master cylinder. Then front negative cable alone to the body/buss bar ground and frame/body ground. And the back positive battery cable should go to the buss bar positive. Make sure the positive cable from the buss bar to the starter is not shorted. Good Luck. I remember your post a few months back with the truck pictured.

 

[richingalveston]

They probably just put a 12 volt starter on it and changed the battery cables thinking that was all that was needed to make it 12 volt. with both alts hooked up and no major butchering of the wiring harness then you are most likely making 24 volts when the motor is running.
yes, pics would be good.
The starter is probably for sure bad now.

The stock wiring puts 24 volts to the starter solenoid through the relays under the dash (see doghead mod). If the batteries are not hooked to the 24volt buss bar and only to the starter then you would not get 24 volts at the relay.

as stated above the 12 volt bus bar is near the master cylinder next to glow plug relay. The 24 volt bar is behind the batteries.

Leave the batteries hooked up as you found them but disconnect from the 24 volt bus bar (large one next to batteries) Go to the relay under the dash and see if you have 12 volts. IF so then the wiring has been changed because this should have no voltage when the batteries are not connected to the 24 volt bus bar.

Check the doghead mod for the directions with regards to the relays under the dash. you should be able to tell if the wiring has been changed by determining what voltage you have on the wires at this relay with regards to how you connect the batteries.

If 12 volts were connect to the 24 v bus bar then there would have been some fire works at one point and probably burn up the passenger alt. The passenger alt is the 24 volt alt and the drivers side is the 12 v. They work just like the batteries. The drivers side alts produces 12 volts which gets input into the passenger alt and 24 volt comes out of the passenger alt.

 

[radbaddad]

They probably just put a 12 volt starter on it and changed the battery cables thinking that was all that was needed to make it 12 volt. with both alts hooked up and no major butchering of the wiring harness then you are most likely making 24 volts when the motor is running.
yes, pics would be good.
The starter is probably for sure bad now.

The stock wiring puts 24 volts to the starter solenoid through the relays under the dash (see doghead mod). If the batteries are not hooked to the 24volt buss bar and only to the starter then you would not get 24 volts at the relay.

as stated above the 12 volt bus bar is near the master cylinder next to glow plug relay. The 24 volt bar is behind the batteries.

Leave the batteries hooked up as you found them but disconnect from the 24 volt bus bar (large one next to batteries) Go to the relay under the dash and see if you have 12 volts. IF so then the wiring has been changed because this should have no voltage when the batteries are not connected to the 24 volt bus bar.

Check the doghead mod for the directions with regards to the relays under the dash. you should be able to tell if the wiring has been changed by determining what voltage you have on the wires at this relay with regards to how you connect the batteries.

If 12 volts were connect to the 24 v bus bar then there would have been some fire works at one point and probably burn up the passenger alt. The passenger alt is the 24 volt alt and the drivers side is the 12 v. They work just like the batteries. The drivers side alts produces 12 volts which gets input into the passenger alt and 24 volt comes out of the passenger alt.

MUCH HELP THANK YOU! Batts were hooked to 24 buss. There was literally no starter wire only the small purple. I prob should have checked here before willy nilly hooking stuff up. I think I have a 350 starter . Will check and try tomorrow.

 

[richingalveston]

research the doghead mod and use the wiring at this relay to determine what you have.
just be careful, some of the wires at this relay are always hot when the batteries are hooked up

 

[cucvrus]

The 350 starter will be 12 volt. It will not operate on the CUCV 24 volt 6.2. And you do not need to modify the starter relay. After 25 years of owning over a hundred CUCV's I never modified one. I have changed a few. But most times the burn down occurs from other factors in the system. Think about it. The truck is over 30 years old and you are going to improve it by hacking the wiring harness, Not my truck. But do as you wish. I think the correct starter and some group 31 batteries and go at it. Heck tow it East to I 81 exit 90 and I will get it running for you. It worked for a few others. Send CASH. Good Luck.

 

[radbaddad]

Does the starter engagement occur as soon as you hook up the batteries? The front battery should be positive cable and connect to rear negative battery. From that negative post a lighter 10 gauge wire will run to the 12 Volt power post near the master cylinder. Then front negative cable alone to the body/buss bar ground and frame/body ground. And the back positive battery cable should go to the buss bar positive. Make sure the positive cable from the buss bar to the starter is not shorted. Good Luck. I remember your post a few months back with the truck pictured.

No starter only engages with key. Only winds on aeries hook up but things get hot. Batteries are not hooked as you say. Thanks for help. will get deeper into this tomorrow.

 

[MarcusOReallyus]

Hey, here's an idea. Since you don't know which way it's wired, stop changing things! Stop testing by just blindly applying power!

That's great way to fry things.

 

[radbaddad]

Hey, here's an idea. Since you don't know which way it's wired, stop changing things! Stop testing by just blindly applying power!

That's great way to fry things.

Yeah thanks Marcus. How about i just chuck a gas motor in it since i cant get it started. My current options are never start it or take a chance.

 

[radbaddad]

The 350 starter will be 12 volt. It will not operate on the CUCV 24 volt 6.2. And you do not need to modify the starter relay. After 25 years of owning over a hundred CUCV's I never modified one. I have changed a few. But most times the burn down occurs from other factors in the system. Think about it. The truck is over 30 years old and you are going to improve it by hacking the wiring harness, Not my truck. But do as you wish. I think the correct starter and some group 31 batteries and go at it. Heck tow it East to I 81 exit 90 and I will get it running for you. It worked for a few others. Send CASH. Good Luck.

What people fail to understand is. I am not necessarily trying to change it. I am trying to figure out if someone has. I just want to start the thing.

 

[Miah]

I'd agree with marcus on that. When trying random things to guesstimate what you have, you run the risk of frying the system & if that happens then your chances of successfully starting the truck will dramatically drop because you still gotta figure out what someone else did AND repair the damage you accidentally caused.

Maybe instead start with how you want it to be wired. 24v or 12. Pull the starter & inspect, if there's no ID on it to tell you which it is then look around for a local rebuilder who could test & tell you(and if need be convert/exchange it for the voltage you want). Then get the wiring diagram of how things need to be for that starter & match the truck to that. Hooking the batts up & trying to fire it will be the final step once you know all else is ok

Good luck & pls keep us informed on what you find out.

 

[MarcusOReallyus]

My current options are never start it or take a chance.

The other option is to TEST things with a meter, instead of with a battery. Meters won't fry things.

 

[cucvrus]

Did this truck ever get started or at least figured out. I was out cutting down big trees and hauling wood with the M1028. I know there was more than enough time to get this truck started. Watching from afar can be just a inpatient as being there. Good Luck. Report back on your findings. Seems like a few wires and cables need resituated and a correct starter put in place. The help line is still open.

 

[radbaddad]

The other option is to TEST things with a meter, instead of with a battery. Meters won't fry things.

The problem is i did not know if things were incorrect or not. You are obviously a way better cucv mechanic than me. I assumed that it was correct because the previous owner said it ran 15 years ago.

 

[radbaddad]

Did this truck ever get started or at least figured out. I was out cutting down big trees and hauling wood with the M1028. I know there was more than enough time to get this truck started. Watching from afar can be just a inpatient as being there. Good Luck. Report back on your findings. Seems like a few wires and cables need resituated and a correct starter put in place. The help line is still open.

No. I did the 12 volt conversion and found out that someone had changed a few wires but not everything. After making the mods starter will not crank. Just clicks. I am pretty sure it is a 24volt starter but some wiring had been charged to 12 but not all. I kinda quit looking here when people decided bashing and reporting me was easier than offering solutions. richingalveston was a big help. I only converted to 12 so i could know it was wired properly. I may change it right back to 24. But first I must try a know 12volt starter. Will try again later in the week.