Glow plug issues now

[JustinC00]

Hey all,
I went out to start my truck and was in the middle of a compression test from last night. I tried to start it and forgot to plug in the fuel shutoff. Anyways, as I figured it wasn’t gonna start, I noticed the glow plug light doesn’t come on anymore and I have no clue where to start. The glow plugs are new, and I live in a moderate climate, but I saw smoke from the firewall and have no idea what wire I could’ve burned up. I check all around and everything seems okay, I can’t really tell as the wiring is a mess. Do y’all think I burned up the controller. I have no ideal when that was last changed. And the controller I’m taking about is behind the intake. The system was updated to the 1987 glow plug system( zd9 and the controller at the back). Please help I took out the old controller and it looks so bad, covered in soot and oil and nasty. Like it hasn’t been changed in awhile

 

[Cubey]

Asuming wires aren't burned to a crisp, the relay on top of the controller might be bad. Try tapping it with the plastic handle of a screwdriver then see if it activates. The one on my F250 had that issue. I replaced just the relay, problem solved.

 

[hacked89]

You saw smoke, and now you have no power. Something burned up. There's a fusable link supplying 12v to the gp controller relay that could be what you saw go. You said it's a mess of wiring and you aren't very familiar with it. Inspect the controller and relay for where the smoke came from and start to trace the wires backwards.

 

[lotzagoodstuff]

The early controllers are pretty notorious for failing.

 

[Cubey]

The early controllers are pretty notorious for failing.

The original factory installed controllers for 83-86 6.9 are electromechanical and are the ones that can fail.

I should probably spend the money to replace the one still on my RV. At least, I think it is one, unless that's just a funny plastic collar that's not part of the controller.

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Modern replacement ones are solid state and can't fail in the same way. A Motorcraft Solid State controller:

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[Big Bart]

You mentioned above you updated to a newer controller. What style is it? Like the one above that Cubey is showing or like the one on the 7.3 where the controller and relay are one unit and a square brick?

If you have the 7.3 style they are set up to only turn on the glow plugs for about a second if 3 or more glow plugs are bad or are not hooked up. When you did the compression test likely you removed the glow plugs. If one or more glow plugs broke upon removing, you did not plug them all back in, or you on accident broke part of the glow plug wiring harness the system will not work properly. I would start there and see if it’s a simple fix.

If not this is a good video to help you test the wiring to the glow plug controller.

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[IDIBRONCO]

Cubey, the top piece that you are talking about in this and your thread on these controllers is not part of the controller. It's a part of the wiring plug. It's what actually locks the plug down onto the controller. You can see the two plastic ears that fit down underneath the lip on the top of the controller. To unplug the wires, you squeeze the plastic sleeve that you're asking about from the sides 90* from each ear.

 

[Cubey]

Cubey, the top piece that you are talking about in this and your thread on these controllers is not part of the controller. It's a part of the wiring plug. It's what actually locks the plug down onto the controller. You can see the two plastic ears that fit down underneath the lip on the top of the controller. To unplug the wires, you squeeze the plastic sleeve that you're asking about from the sides 90* from each ear.

Ahh, ok. I never touched it since it's working. I started a new thread about ID'ing controllers, mechanical vs solid state.

 

[IDIBRONCO]

I saw that and it was the other thread that I mentioned. I have no answers on the different types.