24 volts everywhere!

[Chupacabra2]

Hello all. I am new to Steel Soldiers. I have read several of the helpful tips, and plan on starting with the resistor bank bypass. I will most likely follow up with the 12v conversion (roscommon). I believe that something may be wired incorrectly, however, I'm not sure where. The problem started with the truck not starting, along with the "WAIT" light for the glow plugs not turning off. I discovered that 24v went straight to the glow plug relay and fried the plugs. I cut and insulated the wire coming from the glow plug resistors to the glow plug relay. Since then, I have used either in very small dose to start vehicle. The 12v bus at that time still read 12v, but I wasn't sure if I could tap into it for the glow plugs. Now I have 24v's everywhere. Even the 12v bus reads 24v. Since the wire from the resistor bank is removed from the equation, what could be causing 24v on all wiring? Could it be one of the alternators? going to check the 12v bus without the key in, or truck running. All input will be greatly appreciated.

 

[Chupacabra2]

Well... I do indeed have 24v at the 12v bus without the key in the ignition.

 

[TGP (IL)]

I think I would disconnect the Batteries so you don't burn anything else up.
Probably to late, but disconnect them anyway, before you burn it to the ground.

You need to start reading the stickies and TM's.
Read,Read Read!

BTW,
Once the glow plugs burn out you will see 24 Volt at the relay coming from the resistor.
Resistor needs a load to resist, so as the plugs fail the voltage climbs until there all out.

As far as 24V at the 12V buss something is melted or the batteries wired wrong.
Have you changed anything Alt's,Etc. ?

And WelCome

Tom

 

[Tinstar]

I would stop messing with the truck until you read up on the GP system, etc.
Like TGP said, disconnect the battery's for now.
Your GPs are fried. Maybe other things too
One thing at a time. Read, Read, Read the TMs and old threads.


There is no reason to convert to 12v if everything is working unless you just want to.
The stock 12/24 setup works great and easy to maintain once you understand it.

 

[doghead]

Show us a picture of what you are calling the 12v buss where you're getting 24 volts.

 

[cpf240]

By the way, unless it is under load - ie the glow plugs are 'on', you will always read 24v at the input side of the glow plug relay - in a stock system.

 

[Chupacabra2]

I just found and joined this site... I think I have read every helpful tip sticky I thought relevant. I do not know what wiring was done before I bought the truck. Everything was fine for about the first 2-300 miles. then the GP light wouldn't turn off and the truck wouldn't start. The wires at the alt's does have some damage from rats or age. I understand that the glow plugs have resistance, but I do not understand your explanation of the voltage from the resistor. As I understand it, the drop down ballast... resistor banks job, is to drop the voltage to 12v prior to reaching the GP relay. I will dig into it some more when it stops raining. Oh, I also have the TM and have spent hours reading and checking resistance on the GP card, relay, and at the fusebox. I thought, perhaps, someone might have some insight that might point me in the right direction rather than assume I don't have a TM, or know how to read.

 

[Chupacabra2]

Doghead... Pic of 12v buss

View attachment 12v.conversion.pdfThe 12v junction block is found on page 8, photo C. Thank you for taking the time to help me figure this out because it doesn't make any sense.

 

[Chupacabra2]

Thank you for the information, I did not know that. I spoke with a motor pool SGT, and he said they used to put 24v HMMV GP's in the M1009's and bypass the resistor bank. He stated the GP's would last about 3yrs that way. I haven't seen anything but the 12v bypass listed so far. Would you know if that (24v bypass) would work? Would there be an advantage? and where would one get a 24v GP relay... from a HMMV? Just throwing it out there, you all know more than me when it comes to the m1009.

 

[Chupacabra2]

Thank you Tinstar. And if I already sent this out I apologize, getting used to reading and posting threads on this site. I just wanted to say I worked with the 160th in Taji, Iraq, 2010-2011. Nothing but respect for them, great group.

 

[doghead]

Ok, that indeed is the 12 volt "buss", you referred to. You definitely should not see 24 volts there.

As for the resistor, it's just a piece of wire, it is not magical. It has to be used in a complete curcuit to do its job(resist). That is why you will read 24 volts at the relay until the curcuit is complete and there is a load(good glow plugs).

And just to stop any confusion, the resistor has nothing to do with the 12v "buss" that supplys the 12v portion of the vehicle.

About using 24v glow plugs, they will not work correctly with the stock GP controller card(it senses voltage) and controls based on seeing a drop when the gp's are on.

 

[Skinny]

I remember trying to find "24v" glow plugs for a 6.2 and could never find an actual plug even for the HMMWV listings. I was thinking of just doing a simple push button solenoid control and feed them all right from 24 volts but never did because it doesn't exist for our application. I could be wrong but remember ending that journey years ago and just ran AC60s doing the bypass because it works fine.