Glow Plug Bypass - not working

BeastMaster

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I am a little concerned...

I do not like changing things out until I am pretty damm sure they are bad.

Try this... On that pushbutton, can you get to the wiring... The screw terminals on the back of the switch. Short one terminal to the other with little screwdriver, paperclip, test clip, whatever. You should hear the glow plug relay pull in.

If you can do it by shorting the terminals, but can't do it by pushing the button, it's definitely the switch.

You should get a little arc too. It takes about four amperes to pull in the stock glow plug relay. It's enough to make a little bit of spitz when you attempt to make contact.

Actually, I am concerned with your photo of the relay. You show the two big high current wires connected to the northwest and southeast terminals... And one little wire connected to the little southwest terminal, and nothing connected to the little northeast terminal. Something is fishy here. You have to give the coil some power to pull in.

I think you have a bit of wire tracing in your future. From what I see, I doubt it ever worked like that.

I think you need to get some sort of fused 12V key on power to one of those small terminals, and ground to the other through your pushbutton...

You gotta get power to that coil...

But first, I would follow IDIBronco... Find out first what's killing off your starter. It's a pretty straightforward circuit... Your main challenge will probably be finding the physical location of the points you need to test. There are some wiring diagrams on this site for this.. I don't have their url right now... If I find them, I'll come back and edit them in.
 
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IDIBRONCO

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Whats the alternative option for powering the glow plug harness besides using the solenoid?
You can do like Philip1 said. Personally, I would just stick with the solenoid. It's already wired into the harness so it's easier to use that way.
 

wrecked

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I've had good success over the years using generic Ford starter solenoids (200a I believe. Usually bought the one for the 4.9l six gasser) for tractor glow plug circuits and used the momentary switch to complete the ground, not on the hot side. Before age took most of my brain cells permanently hostage, I calculated the max amps for a set of 8 GPs would draw at most 80a. Likely more for the 10 foot longs on psd's? But more or less confirmed the load using an ammeter at some point in the blurry mists of time. Never had that solenoid fail, even when the dairy farmer in question fell asleep with his finger pressing the button.

GPs, buttons, wiring, connectors etc came and went, but not the solenoid. Think of it as a very robust relay. Just don't use one from a lawnmower! Low amp energized, continuous use rated solenoid would be your best bet, and use at least 10g wire.

Edit: of course this all assumes the oem circuit is *****.
 

RSchanz

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I am a little concerned...

I do not like changing things out until I am pretty damm sure they are bad.

Try this... On that pushbutton, can you get to the wiring... The screw terminals on the back of the switch. Short one terminal to the other with little screwdriver, paperclip, test clip, whatever. You should hear the glow plug relay pull in.

If you can do it by shorting the terminals, but can't do it by pushing the button, it's definitely the switch.

You should get a little arc too. It takes about four amperes to pull in the stock glow plug relay. It's enough to make a little bit of spitz when you attempt to make contact.

Actually, I am concerned with your photo of the relay. You show the two big high current wires connected to the northwest and southeast terminals... And one little wire connected to the little southwest terminal, and nothing connected to the little northeast terminal. Something is fishy here. You have to give the coil some power to pull in.

I think you have a bit of wire tracing in your future. From what I see, I doubt it ever worked like that.

I think you need to get some sort of fused 12V key on power to one of those small terminals, and ground to the other through your pushbutton...

You gotta get power to that coil...

But first, I would follow IDIBronco... Find out first what's killing off your starter. It's a pretty straightforward circuit... Your main challenge will probably be finding the physical location of the points you need to test. There are some wiring diagrams on this site for this.. I don't have their url right now... If I find them, I'll come back and edit them in.

The open space on the solenoid is questionable and you're right I should figure out what that is. The solenoid is getting power directly from the battery positive on the southeast corner of the picture. I've tested it with the ice pick just to double check when I was tracing the wires to figure out what went wrong.

I took the button off and did a continuity test. The button definitely did not work as the continuity test proved. I went to Napa bought a new button (same kind) and installed it. In the meantime I snipped a small segment of the red wire off to figure out the gauge and add an inline fuse. Napa didn't have in line fuses that would work so I crimped it back together and called it a day. The glow plugs work now (as indicated by the glow plug light) and the truck starts. Albeit since the little situation it seems to have trouble starting but I'm curious if it's just a combo of chillier mornings and me not holding it long enough (6-7 seconds).

I will say that the wiring almost certainly has some sketchy aspects to it as most older trucks I've owned do. I've put over 3,000 miles on the truck since I got it less than 1 month ago. So far nothing seems terribly wrong.
 

snicklas

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OK. The different style were run differently...

The 6.9, in the head style controller supplied +12 to the solenoid to power it. A simple manual bypass would be to supply a push button switched +12 to the same post.

The 7.3, on the back of the intake (or valve cover for some turbo applications) supplies a ground to the solenoid to power it. So you put a push button switched ground on the post where the white wire is to activate the solenoid.
 

RSchanz

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I’m not sure how it could be related but now when i start the truck it fires up fine then almost dies right after and just has a funky time for a second. I think the cold timing advance never actually worked and I’m wondering if now it’s trying to? Any ideas? New thread?
 

wrecked

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Well, turns out I just had a similar problem. Check your ignition switch on the column. I could be mistaken with your truck, but it's a simple idle boost solenoid, no?

Edit: I should add that I'm not even a novice with these ford systems and anything I say should be followed immediately by a large swig of tequila. Mescal preferably, with a thin slice of lime chaser.
 
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RSchanz

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Well, turns out I just had a similar problem. Check your ignition switch on the column. I could be mistaken with your truck, but it's a simple idle boost solenoid, no?

Edit: I should add that I'm not even a novice with these ford systems and anything I say should be followed immediately by a large swig of tequila. Mescal preferably, with a thin slice of lime chaser.


Haha, fair enough. Can you elaborate on your idea? Besides following the wires out of the column I'm not sure exactly what you want me to check.
 

IDIBRONCO

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I think the cold timing advance never actually worked and I’m wondering if now it’s trying to? Any ideas? New thread?
You could check to see if there's power to the timing advance and the fast idle solenoid. If there's no power there, check to see if there's power to one or both sides of the controlling "switch". This is screwed into the passenger's side head right behind, below the thermostat housing. Sometimes, there may be some dirt (or something similar) on the blades of the switch keeping it from getting good contact with the plug that goes on top of it. On my Blue Truck, I thought it wasn't working so I started to replace it, but I decided to check for good connection first, I wiggled the plug a couple of times and the plunger on the fast idle solenoid popped out. It's worked fine since then. Yes, the key was on. You do have to have the key on in order to get power to the switch.
 

RSchanz

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You could check to see if there's power to the timing advance and the fast idle solenoid. If there's no power there, check to see if there's power to one or both sides of the controlling "switch". This is screwed into the passenger's side head right behind, below the thermostat housing. Sometimes, there may be some dirt (or something similar) on the blades of the switch keeping it from getting good contact with the plug that goes on top of it. On my Blue Truck, I thought it wasn't working so I started to replace it, but I decided to check for good connection first, I wiggled the plug a couple of times and the plunger on the fast idle solenoid popped out. It's worked fine since then. Yes, the key was on. You do have to have the key on in order to get power to the switch.

I just ordered a new return line kit from Russ because they're leaking slightly and I don't think this helps my case in terms of potential air in the fuel system. It's shipped today so once I replace that I'm going to re-visit the stumbling rough idle right after starting.

In the meantime, the small pump or plunger, if you will, isn't making contact with the throttle lever there. There is probably a millimeter or two of space. I'm imagining when the truck is started cold this pump is supposed to stick out and increase the throttle right?

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wrecked

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You could check to see if there's power to the timing advance and the fast idle solenoid. If there's no power there, check to see if there's power to one or both sides of the controlling "switch". This is screwed into the passenger's side head right behind, below the thermostat housing. Sometimes, there may be some dirt (or something similar) on the blades of the switch keeping it from getting good contact with the plug that goes on top of it. On my Blue Truck, I thought it wasn't working so I started to replace it, but I decided to check for good connection first, I wiggled the plug a couple of times and the plunger on the fast idle solenoid popped out. It's worked fine since then. Yes, the key was on. You do have to have the key on in order to get power to the switch.
Ya what dude said... lol. Thought I'd take a lucky stab at her and wound up losing an eye. Shoulda listened to my mom about putting eyes out...
 

RSchanz

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Grounded the Circuit tester in the door jam and closed the door forgetting it was there and broke it two days ago. :Thumbs Up
 
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