Glow plugs FRYING. 24V constant

[sermis]

OK I am totally baffled.
The glow plugs will not work and cycle and keep frying.
HMMWV came with fried plugs and bad PCB box. Replaced plugs, PCB, and controller from known good truck. Plugs fried. Replaced PCB with new box, has 3rd access port on box, new controller, new plugs and the plugs still will not cycle and they burned up again. I checked glow plug wire with key on, truck not running. 24V. 20 minutes later key still on not running and still 24V on the plug wire. The wait light when the key is turned on will flash 10-15 times then go out but keeps 24V to the plug wires.. .
I have another glow plug harness I am rigging through a relay and push button with a timer, work around fix.
I would still rather fix it correctly but I am out of ideas.

 

[Jakob1944]

Are you putting 24V plugs......

 

[sermis]

Yes on 24V plus.

 

[Jakob1944]

Yes on 24V plus.

Ok.......my quest would be to disconnect the batteries, remove the box and open it up to see if you could find the obvious.....True you can't see some components that are kaput.....

I would also check the trouble shoot section of the TMs


maybe so help

 

[sermis]

I don't really think it's the box causing the problem. The wait light just flashes on and off 10-15 times. Never counted. I used a known good older style box, matched controller, and new plugs and the same thing happened. That box and controller was put back into my other truck and it worked correctly.....
I installed a new Nartron box with 3rd port, matched controller, and new plugs and same thing.
Shot in the dark but can the alternator cause any issues?

 

[jeffy777]

I think you have a battery problem. You probably don't have enough power to warm the glow plugs. I used a 24V battery charger/starter(Schumacher SE-3000). Try starting it with something like that. I do not know what all the control box does but I would assume knowing power levels where too low for the glow plugs was in the design. (2 cents from a man with 4 cents of thought)

 

[sermis]

That's an idea. Batteries are older and might be weak but they will crank the truck over for ever. When warm weather I just crank till it will bust off.

 

[jeffy777]

Sorry. I was just putting out an idea. I think there is only the wiring, control-box, batteries, switch, and glow plugs as part of that system. You replaced everything except wiring and batteries. And you are reporting numbers which make me think the wiring is ok. Sorry, good luck. I can't wait to read what the resolution you find. Good luck.

 

[sermis]

Also wondered about alt too. It's a duel voltage 14v 28v but using a test meter I can't get any 14v readings.

 

[Retiredwarhorses]

Replace your engine wiring harness....check all your grounds as well.

 

[sermis]

I was thinking wiring harness too. I've cleaned grounds and added a grounding harness.

 

[Retiredwarhorses]

The problem is that it starts to get expensive throwing parts at a problem, especially electrical.
a new engine harness is relatively simple to install and takes any guess work out of any bad connections.