I get no voltage to the relay when I turn the key on. So my controller is either bad or disconnected. I also don't get a GP light.

I triggered the relay for 5-7 seconds and still no start. Did that a couple times, no start. I have to test the plugs individually, but I suspect a few or all are bad or there's some hackery in the wiring.

So, onto my question. I saw the post about the 6.0 GP harness, but it requires the bullet top GP's. No problem, I might have to buy a set... I've seen conflicting posts about the 87+ glow plugs being 6v or 12v and I'm completely lost now. If they're 12v then all I have to do is put them in, modify the 6.0 harness, attach everything to the relay and trigger it with a momentary switch.

If they're 6v... ??

Manual seems to be the easiest, most durable solution unless I'm missing something. I don't mind hitting a button for a few seconds before starting the truck. Hell, I want to swap in a ZF-5 so I have no problem with manual control..

Can someone help a diesel noob out?

 

First off, what is a glow plug?
A glow plug is simply a small resistive heater coil. If you apply voltage to it, it will heat up.
The more voltage, the quicker it heats up. With a given voltage applied to it, it will heat up to the point where the glow plug radiates heat to the atmosphere(or anything else around it) as fast as it is being generated.
On top of that, a glow plug(or most anything else, for that matter) can only get so hot before it simply melts.

Thing is, you don't need to apply a constant voltage to your glow plug. If you only apply a short pulse of power, you can apply a much higher voltage(and thus make it heat much quicker) without burning it out.

In addition, there is an interesting property of most resistive heating elements: The hotter they get, the higher resistance they are. Higher resistance means less current flows through it, means less heating. So you can end up with a "self-limiting" device. Think about an incandescent light bulb - it gets bright really quickly, but doesn't melt itself; that's the "self limiting" factor at work here.

Now, how does this apply here:
6.9/spade-style glow plugs are slower-heating(higher resistance) glow plugs. If you put a given voltage to both a 6.9 and 7.3 glow plug, the 7.3 plug will glow quicker than the 6.9 one.

As far as a manual setup goes, you can technically use either type. The issue is simply how long you hold the button.
And there's nothing saying you need to use the stock wiring harness, either.
I chose to use 6.9 style glow plugs, a custom harness made from individual links of 12ga wire to each glow plug, and the resistor from a 7.3 controller to reduce the voltage even more.
What this means for me is that I have to hold the button longer than any other setup - a good 15 seconds or so. But it also is more forgiving; I have to worry less about overheating, because the number of seconds between "hot" and "too hot" is probably another 15 seconds.

I'm also the guy which took a 9th glow plug(wired into the rest) and stuck it on my dash, as an indicator - I watch that one to tell me how hot the others are.

I can give you some more pointers and info too, just ask.

 

Yeah, but the 6.0 harness is cool looking...

I follow you on the differences. I'm also familiar with heat adding resistance and being limiting. I've played with enough bad grounds on these trucks...

15 seconds is a little past where I want to hold a button, but that's the fun of customizing. Maybe just run the 86 style, clean up the harness and get over not having the "cool" harness. That I assume will put me in the 5-10 second range depending on how cold it is.

 

I have ran manual glow plugs on several engines. Never had any issues while exercising good judgment.


Good judgment is developed on poor experiences.

 

That's for sure... I've killed a couple of glow plugs holding my button too long because it wouldn't start, even though my indicator said it was hot enough.
Problems were:
1. Unplugged the FSS to shut it off the night before(when looking under the hood), didn't plug it back in...
2. Was /way/ too cold, fuel was gelling. Ended up using like half a can of ether and 8 minutes of cranking before it finally caught.
Aside from those(where the glow plugs were working just fine, I just overdid it half-knowingly), I haven't fried any glow plugs using my system.

 

I use a momentary push button on mine and haven't had any problems. My process (hold) time was hit and miss until I learned what my truck needed at a given temperature- it is still guesswork. I still err on the cooler side, I think, lol. Yesterday, at 28 degrees, I held my button for 8 seconds, cooled for 6, and held for 8, cooled for 4 and it fired right up.

I remember someone, on here, testing all sorts of GP's for longevity and the Beru's were the best plug.

The nice thing about the controller is the controller takes all the guesswork out of it. The nice thing about a push button is that a low compression engine could benefit from an extra glow cycle.

Has anyone recorded the timing of the controllers at given temperatures?

Is there a diagnostic chart, for the controller, of the cycle time/temp spec's one could memorize?