m1028 glow plug issue

[The Ginch]

Hi guys never knew about this site. Anyways i am on my second military rig well actaully second ex military then fire dept brush truck. Got to love FD wiring messes.

heres my issue. with key off the GPR has power to the top terminal only. With the key on in run i have power to all the terminals except the glow plug large bottom lug. If i ground one of the two smaller lugs on the GPR the relay clicks and the plugs work as they should. is this an indication of a bad controller card?? getting tiring haveing to pop the hood every time i need the truck.

Would the push button mod work here? seems most push button mods i have seen add 12v to the relay.

i searched but must be missing this. thanks for the input.

 

[doghead]

The controller switches ground to the light blue wire, to activate the relay.

 

[doghead]

Also, we have technical manuals with schematics and troubleshooting a and parts diagrams available for free.

We also have stickies and wikis, that explain all this as well.

And we have about 8 years of forum threads covering this also. This is a daily occurrence, so just a little browsing through a few days of cucv postings should enlighten you as well.