Another Glow Plug/Solenoid/controller problem

[HOGGIN84]

Well Well, While deployed to Afcrapastan this year, i bought a M1008. My buddy was staring it for me for a few months and the all the sudden he said the GPs stopped cycling.

He came to the conclusion it was the four post solenoid on the drivers side with 2 copper/2 silver post, as he tried to jump across the old one with no joy, replaced it with a seemingly similar solenoid again with no joy, he ended up basically making a manual GP switch by jumping out to the small post marked "S" to a toggle switch inside the cab, which i am not fond of! my question is what cycles the GPs?? the solenoid? or the Circuit board underneath my dash??...or am i completely off base??? please help as i want this thing to cycle normally without me really messing something up!!! Thanks in Advance!!!!!

Go Hogs, Happy New Years and God Bless America!!!...im out

 

[cpf240]

The GP card cycles the GP relay on and off. It _must_ be an isolated relay, meaning no conductivity between the small terminals and the relay case / mounting tabs. If it has an "s" on one of the terminals, it is probably the wrong relay and is not isolated. Using a non-isolated relay can cause damage the the GP controller card.

Check out the CUCV FAQ thread, it has all the info you need about choosing the proper relay.

It may look like a standard "starter" relay, but it is not!

Good luck, stay safe, and Thank You for your Service!

 

[HOGGIN84]

I should have mentioned the truck is converted to 12v??? does that matter???.....thanks for the reply

 

[cpf240]

I should have mentioned the truck is converted to 12v??? does that matter???.....thanks for the reply

The GP controller card is 12v no matter what. The GP relay that is controlled by the GP controller card is 12v for its coil, and, in a stock setup, switches 24v through the big resistor bank on the firewall to the GPs.

The combination of the resistor bank and the resistance of all the GPs drops the voltage the GPs see to about 12v. That is until one of the GPs fails, then the voltage seen by the other GPs goes up, often leading to a cascade failure.

In any case, the 12v conversion should not affect the operation of the GP controller card and GP relay. It still needs to be an isolated relay.

Of course, since we are talking about a truck that is no longer in the stock configuration, I can't say with 100% certainty what else might be going on.

You may want to post pictures of the conversion, etc. Many on the forums here have lots of experience with this sort of thing, and pictures can help in determining any problems.

 

[idM1028]

It's usually preferred when converting to these trucks to 12-volt to do the Roscommon conversion (http://www.roscommonequipmentcenter.com/news_notes/nn10.pdf) since it is the most widely known. Just browsed through the instructions and there is no mention of replacing the GP relay. The only thing that is mentioned is the removal of the GP resistor bank. I know on my truck at least, there is 24 volts running to the GP relay however, I don't think it would make that big of a difference since it sounds like the GP's were cycling fine before. It is recommended that if you convert to 12 volts to change out the glow plugs. Check the wiki for exactly which ones.

 

[HOGGIN84]

Ok thanks for the info gents!!!!!! What symptoms will I have if my plug circuit card is bad????

 

[cpf240]

Ok thanks for the info gents!!!!!! What symptoms will I have if my plug circuit card is bad????

Hard to say, could work intermittently, not at all, stay on too long, not stay on long enough, burning electronics smell, irritating rash, itching...

There are a few people on here that diagnose and repair them, as well as build upgraded modern versions. I think one is antennaclimber and the other has a website called cucvelectric. I've heard good things about both, and have bought alt rebuild kits from cucvelectric.

 

[Tulsafireman]

Sounds like your on the right track with a bad GP Controller Card if the tollge switch is firing your relay and making your GP's work. I did the roscommon 12V conversion to my M1009. After that there is no 24V left anywhere in the vehicle. The only thing on the CUCV's that was 24V was the starter. Once converted is just a 12V truck. BTW, be sure to bypass the second starter relay under the dash (you can find the instructions in the CUCV Wiki) so it doesnt stick your starter and burn it up. I had the same problem with my GP's. Mine was the cascading failure. Relaced all with AC60G's. I relaced the GP relay (NAPA ST85) and put a button inside like yours is set up. I prefer controlling my GP's manually (like my tractor) on for about 8 to 10 seconds and it fires every time. I didnt want to rely on the GP controller card, it just something else in the circut to go wrong. If it is your controller just search the site for GP controller card and there is lots of good info here. Even a place to buy a replacement card or get yours rebuilt. Good luck with your CUCV. They are a blast. Remember, if its electrical clean it, if its rubber replace it. Everyjting you do will make your truck more reliable and fun to drive.

 

[HOGGIN84]

THANKS AGAIN for all the replies @ Tulsafireman so you dont have a Controller Card???? will it not harm the GPs doing it manually?? in the long run????

Also are you an USAF FF??

Im in the AF for 9 years now, CE Hvac troop!!! Currently at hurlburt field RED HORSE Sq!!!

Thanks again

 

[Tulsafireman]

YW! Left the controller card under the dash. Not sure why. I need to take it out now since it doesnt run the relay anymore, my push button does that. I changed the glow plugs to AC 60G which are self regulating and I NEVER hold the button down for more than 10 seconds before starting the truck. I think the controller card kept them engaged longer than that.

Yep still in the good old USAF kinda. (22yrs on 05MAR2012) I'm an IMA reservist at Altus AFB now.

My brother in law is a Lt Col at Hurlburt.

No offense but sure glad I dont have to go to Silver Flag anymore

Stay safe bro!