Post#4, almost forgot.

Jason, check your fuel bowl heater fuse. #22 I think but not 100% sure on yours.

 

Call me if you need to Jason, seems we are always getting practice on somebody's glow plug system up here.........

 

Update:

Okay, I finally got a chance with the combination of cold enough weather and not having to get out of here today before checking the GP relay function. The small post closest to the cab with the key on is not hot and the one closest to the radiator is hot. So for some reason, I guess I do not have signal coming from the PCM.

Rich, I will call you in a little while, at a family event giving cousins adjustments, well they are looking at me waiting patiently as I type this....

 

SO far Jason is not getting the 12V supplied power to the back small Post. When he supplied that back small post with a 12V power source, the PCM grounded the power and the glow plug relay worked properly.

So now looking for a blown fuse.

Jason, here's a wiring schematic.

 

I feel like a woman looking at a street map when I see these schematics.

 

it's your GPR........I brain farted. Remove the PCM wire (rear small post) You should see 12V on both posts with the Key On. If not then the relay is bad.

 

Grab 2 beers, a can of copenhagen and just play connect the dots,......

 

when I followed the wires leaving the GPR, specifically the 12V power source supplying the IPR as well - it dawned on me to stop fuse hunting. If the truck is running then the IPR is working so there shouldn't be a blown fuse. So then you disconnect the PCM grounding wire so you know the GP's are not being activated. You should have 12V at each small post. He doesn't - it never showed anything until he put a 12V supply to it. So time for the Stancor Relay and not worry about it again........

 

As it turns out, it was much-a-do about not much. Sorry my mind went all 'worst case scenario" and I threw up the flag of surrender so quickly, but it seems that a confluence of events conspired to activate my paranoia that this truck must have something other than the normal thing(s) go wrong with it, that many times actually is the case for me.
At first when the GP relay that was on the truck went bad about 4 weeks ago, as indicated by the GP LED mod light not illuminating in the mornings, I replaced the relay and as I was tightening up the small lug closest to the radiator with a 1/4 inch drive, I felt it break.

I of course didn't expect that one to work, and it didn't let me down, it did not in fact work. So a few days later after starting the truck in the morning by shorting the lugs with a screwdriver, I bought another relay and installed it, and it immediately did not work. So rather than think it must also be bad, I went to the scenario in my mind that my truck is "special" and something much more complicated than an aftermarket relay being bad right out of the box, MUST be the culprit. But as it turns out, this morning I replaced the relay with a brand new one, (rather than swap the AIH back and forth to test it Rich), and everything works as it should.

Well, at least we have another glow plug relay thread with some nice diagnostics explained by Roland and Rich and some very detailed diagrams for future posters to look back on.

Thanks everyone....

 

It's all good Jason! As long as she's running normal again......its funny how the simple stuff gets overlooked.