Cucv m1010 resistors check and replace / bypass?

[TGP (IL)]

Ok Rich I'm following what your saying ,

"if your front battery has a dead short or dead, you have no 12 volts until your alts start producing. thus you cant heat glow plugs.

if the front battery is just dead, it will produce 12 volts with the 24 running through it so the IP will open. IF the front battery is completely shorted or gone, I don't think the ip will open until alt turns fast enough and I am not sure if the starter will do that."

But here's my take,
If there's no 12V. at the firewall block to feed the 12V side of the truck it's not going to crank over
Because there's no 12V at the under dash starter relay.

So in reality the slave cable would be useless under your scenario?

Would the military have to put even dead batteries in just to jump it?
I think not.

Also I agree that the 12V tap is spiced into the battery cable Rendering it useless with a missing battery to complete
The circuit.
Now I need to study the schematics some to se were else, if any it can get 12V.

I just can't believe that the military would have vehicle that can't be jumped started with an Open battery.
Sure the resistors are supplying power to the GP. but that's it, if no other 12V is present.

Tom

 

[richingalveston]

The system is designed for a jump start of a dead battery. If the front battery is bad, the truck wont run. If the 12 volt alt dies, the truck will only run until the battery no longer opens the IP.

It is a jump start system for a low battery, it is not a fix for a shorted battery. It will not start a broken truck.

The resistor takes the majority of the load of the 12v side for starting only so that what can come out of the front battery is sufficient to open the ip an trigger the relays without to much voltage drop.

People mistake the system for what it is not.

 

[sandcobra164]

I'll just post my personal experience and let it get analysed by people smarter than myself. A few years ago, I left my truck at an event that allowed kids to climb around, flip switches and whatever else. The M1028 cranked up fine and drove home. 2 weeks later, the front battery was dead. Someone had turned the headlight switch to the right to illuminate the bulbs under the dash and that drained the front battery. I backed my deuce down, hooked up the slave cables, waited 5 minutes as instructed before putting a load on the battery and the truck started right up, ran fine but would not restart on it's own. Rear battery was at 12.8 volts but front was at 3.1 volts. I tried to charge the battery a few times but also failed miserably. Put new batteries in and all is fine in the world. The rear battery was probably fine but it got swapped out as well. Now a long narrative to say this. I converted most of my truck and eliminated the resistor behind the air filter years ago and put A/C 60G glowplugs in years ago to 12V. I think the only thing left is the 24V starter. Doghead prompted me through a helpful post on how to eliminate the resistor. I did so and it still starts fine on "lowest in GA" 17 degrees positive temps.

 

[richingalveston]

your batteries were not shorted or missing so the truck was able to jump start from the nato plug. If any one wants an exercise, take your front battery out and try to jump it. or take your front battery cables loose and connect them together and try to jump it.

The jump start does not work in either of the above situations. your front battery was bad that it had a dead cell and would not charge. that is not a shorted battery or a missing battery.

The Nato plug is for jump starting dead and week batteries not broken or missing batteries. The instructions tell you to wait 5 minutes because it is letting the front battery get some power back into it before trying to start so it can power the relays.


be careful running a truck with battery not charging. It will cause your alt to go bad.

 

[doghead]

The resistor takes the majority of the load of the 12v side for starting only so that what can come out of the front battery is sufficient to open the ip an trigger the relays without to much voltage drop.

The resistor is ONLY used for the Glow Plug supply, nothing else!

 

[Recovry4x4]

After dealing with CUCVs for a little while, I will offer this advice. There is no scientific or technical info to back this, just my personal observations. When any of my CUCVs fail to start from a low battery(s), the first thing I check is the voltage of the batteries. If both batts are low, I head for the slave cable. If only one batt is low I grab a jump box or jumper cables and just start it that way.

 

[richingalveston]

yes it only supplies the glow plugs.

If the glow plugs were added to the 12 volt circuit with a low or dead front battery, even with slave cables connected, there is not enough 12 volt power that will immediately come from the front battery to power everything, The voltage would be to low due to the large load of the glow plugs and not allowing the relay's to work.

when you take the glow plug load off of the 12 volt side and put it on the 24 volt side, it reduces the power needed out of the front week battery by over 90% which allows the voltage to stay high enough to energize the relays.

The front battery will act as a transformer and peal off some 12volt power from the 24volt slave cables at the rate at which the battery can absorb the power. you cant force it into and out of the battery, this is why you give it some time once the slave cable are connected. But Until it charges for hours it will not output enough amps to power the glow plugs on the 12 volt side.

hope this helps.

 

[richingalveston]

just going to add a little more info on the jump start of a cucv with damaged batteries.

The front battery is all that is required to keep the truck running. Even with the 12v alt not working it will run on the battery for quite some time if you limit all other 12 volt power.

once the truck is started, the rear battery is not needed to keep the truck running.

If you get in a situation where your front battery is shorted, then you can swap the batteries and a slave cable will start the truck (leave back disconnected). When the slave cables are connected the batteries of the other vehicle are now in series with the truck being jumped so the 24volt side does not see the missing battery.

if your front battery is fully charged because it was sitting in the back position not being used, you should not need the resistor for the glow plugs, the front battery will handle the 12 volt load with glow plugs if it is fully charged. and since the slave cables are connected and rear battery disconnected, there is no starter load on the front battery.

If your back battery was week also then you will need the resistor.


Running the truck without the back battery can burn the 24v alt. up. So if possible take the belt off and just go 12 volt. It will have to be slave started but you can get it home.

There is an option B if you do not have a slave cable but you have to have another vehicle to borrow the battery. Put your good battery in front, the borrowed battery in back. remove alt 2 belt. start truck, remove back battery and put back in other vehicle.

If the battery is shorted, you do not want to leave it connected in the system, it will drain the front battery and ruin the alt.

I have studied this because I plan to take my truck on several day off road trips thus I try to think of all the ways I can to get it home and not leave it on the trail when something happens.

If you are alone and not in a good position to stop, if your gen one light comes on, pull over and check things with a meter but don't shut it off immediately. It may not restart. You can drive for a while on just the battery to get yourself in better place to stop and work on it.

just trying to help
Rich

 

[Sergey G]

Thank you guys again. One more question. I have bought a glow plug switch which is different than my original and I have problem to which of the smaller studs the blue wire from gP module should go to - to the I side or S side? I' m attaching the photo of it.

 

[doghead]

First, test with an ohm meter, or continuity tester for continuity between either of the small studs to the mounting tab. If there is continuity between either of the small studs to the mount, you have the wrong relay.

If that tests ok, then use it.

It makes no difference which terminal (small or big) as long as you simply connect the big wires to the big studs and the small wires to the small studs.

The orange wire must be connected to the output(glowplug) side.

 

[Sergey G]

First, test with an ohm meter, or continuity tester for continuity between either of the small studs to the mounting tab. If there is continuity between either of the small studs to the mount, you have the wrong relay.

If that tests ok, then use it.

It makes no difference which terminal (small or big) as long as you simply connect the big wires to the big studs and the small wires to the small studs.

The orange wire must be connected to the output(glowplug) side.

This one was listed for any 6.2 and 6.5 l chevy engines, why do you think it might be the wrong one?

 

[Sergey G]

It does show 5 ohm to the smaller S stud, nothing to the I

 

[doghead]

What is the brand and part number of that relay?

Correct part numbers are listed in the sticky.

 

[Sergey G]

What is the brand and part number of that relay?

Correct part numbers are listed in the sticky.

Yep.))) it says ford power stroke e and F series. So must be the wrong one? No chance this one will work

 

[richingalveston]

it will work if the terminals are isolated from the case. depending on the amp rating will determine how long it last.

If you have continuity between any of the terminal and the mounting feet then it will not work. If it is isolated it will work.

 

[PJL]

It won't work in the CUCV glow plug system. With the case grounded and applying 12 volts to the S terminal it will close the relay. Which means glow plugs always on.