ok, here's another dillema. My 6.9 won't start in the morning unless I physically jump the two copper terminals on the GP solenoid ( Pass. side fender well). Initially I thought it was due to only 4 GP's working, but I switched them all and still won't start on it's own. The GP light on the dash doesn't come on or anything. I don't hear the sol. (relay) clicking at all. I saw that some of you guys bypassed the control box by installing a toggle switch on the dash, but I'd really like to figure out WHY the problem exists and rectify it properly. thanks again!
-Ryan

 

I had the same problem with my truck but my GP light did come on. On mine it was a problem with the small wire (red and black) going to the solenoid from the starter switch. I put in a new wire from the starter switch to the relay and now it starts every time.

 

Skaterock, jump a wire from the battery positive terminal to the small wire terminal on the glow plug relay that is on the engine side of the relay. When you make connection you should here the relay click and if someone is watching the light on the dash it should light. Glow plugs are working then.

There is a glow plug controller on the back of the drivers side head that dies and kills the whole system. The controller is about 120 dollars from Ford and they are the only local parts store that will have them.

That is the terminal you run a push button hot wire to for manual glow plugs. When the motor is cold, push the button for 10 seconds and start the motor. When the motor is warm, just start the motor and save the glow plugs for when you need them.
When it is real cold, push the button for 10 seconds, wait about 15 seconds and then push it for another 10 seconds, then start the motor.

 

ok. I'll do that test tonight. thanks Dave!
If I do elect to run a momentary switch for the GP's, do I still need to replace the controller - assuming it's bad? Or by bypassing, do I eliminate the need for the control box?
-ryan

 

Skaterock,
I'm not sure if the 6.9 and the 7.3 (which I have) are the same GP relays or not
but
what I was told is that ..
9 times out of 10, the GP relay does not need to be replaced. What happens is that the 'black box' (relay solenoid on top of the controller) is the only thing that fails and not the entire unit. The relay is the same type of relay used on the starter sequence (the black box on the psngr side fender) and is a hell of a lot cheaper than the cost of the entire controller.
I would try changing that before going the route of doing the whole controller.
that's my 2 cents

 

so, there are 2 relays and the control box? I know of one that I am jumping,but I don't see another one for the GP's.
theres another on the fender, but I thought it controlled the starter like a gas motor would have.
Also, I may be going blind, but I don't see the control box. If I understand, there is another relay monted directly on top of the control box? Judging from the wiring diagram in the manual, it should be located to the rear of the engine -right where my turbo is!! I guess they may have moved it. Can anyone (since I've never seen this elusive box), tell me the rough dimensions of it and any identifying markings? thanks in advance!

 

Yup, you are right on track there Skaterock!
The GP controller is directly behind the intake manifold (rear of the engine), under your turbo. You won't see the relay right away, it under a plastic cover (atleast mine is).

Sorry dude if I'm screwing you up -
I just realized that the relay you were jumping is the starter relay (from what you described - on the psngr fender well?)
If that's the case, it sounds that the relay is toast and you need a new one ...
unless your battery is dead?
If this relay is toast, you will definetley not here the GP's clicking because they aren't getting any power.

 

hey dubra,
there is actually a difference between the 7.3 and the 6.9 GP's. I found this out after many hours searching for a pic!! of the 2 controllers on the internet. The relay i was jumping we in fact the GP relay - not the starter relay. They are located within inches of each other. The starter relay feeds the power (in addition to a dedicated 12 signal from the battery) to the GP relay.
The 7.3 GP relay is mounted directly on top of the controller and is shaped like a box, whereas the 6.9 cont. appears to have a bullet-like shape, and the relay is a total separate entity in itself.
I'm pretty sure I have isolated the prob. to the controller, so now I just need to pony up some dough and buy one!
-ryan

 

Well, you learn something new everyday don't you.
Hopefully it's not a huge cost for the part.
How about a salvaged one?
Glad you figured it out.

 

Skaterock,
Sorry for taking so long to get back to you, had a dead computer hard drive to deal with.

The controller does not need to be replaced to run the manual switch.

The manual version other than it is a pain to remember to do for a while is actually better because there are a lot of times you do not need to cycle the glow plugs. Since they are manually controlled they do not cycle when un- needed. This saves them for when you do need them.

Like you go in a store for 20 minutes and when you come out to start the truck and the glow plugs cycle. You should not have to cycle the glow plugs 20 minutes after running the truck. At 10 degrees outside I can normally start mine by just turning the key, no glow plugs, for 3 or 4 hours after the truck was up to temp. If it sits all day, then I cycle the plugs and away we go. When it is plugged in I never use the plugs. Each time I do not cycle the plugs I figure I just bought 1 more day of them working. Make several short trips in a day and the next thing you know your plugs will last months longer.

The other style (square box) of controller was on the 87 6.9 and the later 7.3's.

Most places will be asking around $120 for the old style controller

 

be careful the glow plug controller on the rear of the block, brakes off easily so be patient, if it does your screwed.