1984 f250 glow plug problem
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New User
Joined: Oct 2004
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1984 f250 glow plug problem
We just replaced the controler and the glow plugs in this truck. When it is cold, it will work perfectly. as in the controler will cut on for around 6 to 10 seconds and then back off. Then it will cycle a couple of times 2 sec at a time untill the engine is idleing. Now the problem is, when it is full temp, the controller will come on and stay on. It has already burnt out the new glow plugs and we replaced them again. Any idea what is going on?
Logistics Pro
Joined: Apr 2004
Posts: 4,292
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From: NJ where fun comes to die
Welcome to FTE. I would suggest you install a push button instead of a new controller. It will eliminate the problem. I would guess that something makes the controller think the engine is cold. But I am not a diesel guru, so that is just a guess. If you do a search you will find alot of threads about changing to a push button. I believe you can also convert to the newer style controller, but I know even less about that. Possibly someone else will come along with some better info. Good luck with it.
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New User
Joined: Oct 2004
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Problem is, this is a new controler. As a matter of fact, this is the second new controler. It has to be something in the wireing. When we got the truck the whole stearing column was bypassed. I'm trying to put it back the way it should be and would really like to stay with the controler. I have installed a switch that I can manually turn off the controler so it don't burn out my glow plugs this time.
Junior User
Joined: Oct 2002
Posts: 59
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From: Oregon
Just added the "push botton" to my 85 6.9 this month. Look back over the past 2-3 months and you will see a load of glow plug problems. I added a spring loaded switch in order to allow a longer start cycle for the GP when the temp drops. My GP controller (car quest brand) did not allow enough time of GP cycle times to start below 35 degrees. (The opposite of your problem). This bypass is great, along with a set of new motorcraft GP's ( from autozone). There is a older thread that has the wiring digrahm for doing it, but I don't recall which one. Good luck
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
That is the old style glow plug system.
It is hard to trouble shoot because of all the things it does.
You turn the key to on.
The controller senses the coolant temp to start off.
If the temp is low enough it says turn the plugs on for x seconds and lights the wait to start light.
The light goes out and you start the engine.
There is a latching relay that then senses the voltage from the alternator for x seconds to provide afterglow cycling of the glow plugs to reduce the white smoke at startup.
After the afterglow timer recieves voltage for the x amount of time it turns the plugs off.
So your problem could be;
The coolant temp is not registering at the controller
The alternator is not putting out the proper voltage
The wire from the alternator to the controller is not making good contact
The ignition wire is making intermittent contact and resetting the controller to start the cycle again
You got a bad controller
The relay is sticking on
Bare wires are putting voltage to the relay trigger circuit
The controller ground is not making a good connection.
There is to much or to little resistance in any of the above circuits.
There is 4 or 5 pages in the Haynes diesel manual about trouble shooting that system alone.
It is hard to trouble shoot because of all the things it does.
You turn the key to on.
The controller senses the coolant temp to start off.
If the temp is low enough it says turn the plugs on for x seconds and lights the wait to start light.
The light goes out and you start the engine.
There is a latching relay that then senses the voltage from the alternator for x seconds to provide afterglow cycling of the glow plugs to reduce the white smoke at startup.
After the afterglow timer recieves voltage for the x amount of time it turns the plugs off.
So your problem could be;
The coolant temp is not registering at the controller
The alternator is not putting out the proper voltage
The wire from the alternator to the controller is not making good contact
The ignition wire is making intermittent contact and resetting the controller to start the cycle again
You got a bad controller
The relay is sticking on
Bare wires are putting voltage to the relay trigger circuit
The controller ground is not making a good connection.
There is to much or to little resistance in any of the above circuits.
There is 4 or 5 pages in the Haynes diesel manual about trouble shooting that system alone.
Elder User
Joined: Mar 2002
Posts: 529
Likes: 0
From: France
GP Controller
Hi,
I would go for the manual switch on this one too,a spring loaded push-button,did it on my 86 6.9 and no more problems,here is the link to the wiring diagram:
Controller bypass
I would go for the manual switch on this one too,a spring loaded push-button,did it on my 86 6.9 and no more problems,here is the link to the wiring diagram:
Controller bypass
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