I want to have a back up push button for my glow plugs in case my controller decides to fail, is it possible to have a push button hitched up for a back up?

Also Id like to install a controller off a 87-newer on my 85, is this just a plug and play with the solid state controller, or do I need to replace more than the controller?

 

The way most old style controllers fail is by leaving the glow plugs on.
So probably the first thing to do would be put a switch between the controller and the relay.



In the above picture, you can see where the purple wire has been cut and spliced to two green wires.
To be able to cut the controller power to the relay the green wires would have to run inside the cab to a switch.
Switch on sends power to the relay, switch off disables the relay.

If you want to be able to go either manual or automatic my choice would be a double throw single pole momentary switch.
The switch markings will look like this on the package. SPDT (ON) OFF (ON)
SPDT single pole double throw
(ON) OFF (ON) momentary on - off - momentary on means the switch is off in the center position and both on positions are spring loaded to return to off position


That way when the controller does fail, you can not leave the glow plugs on by accident.

To wire this setup, the wire going to the relay must be on the center terminal of the switch.
The wire from the stock controller goes on the top terminal of the switch, so to get power from the stock controller you hold the switch down.
The bottom terminal gets power from the fuse box, prefferably a switched fuse, so when you push the switch up, you have manual control of the glow plugs.

If you did get power from a switched fuse, the key must be on for either to operate.
And you must push the switch for manual control or automatic control to operate.

If you don't mind risking a set of glow plugs, you could install a SPDT ON - OFF (ON) switch.
This switch will stay on when switched to one side.
So if the switch stays down when pushed to that position the top wire must come from the stock controller and the glow plugs will operate in a normal automatic fashion.
The up position will still be manual on and spring loaded to off.
When this switch is turned to the center position, the glow plugs will be in manual off.

 

Ok that was a lot to read Dave, Ill figure it out. When I first got my truck the guy had wires going to the Controller on the back of the motor, that was when you had to use a push button to start it, so the GP's wouldn't come on unless you had a switch because the ignition was bad.

I just had a problem a month ago with the GP's not wanting to come on after I was done shopping, So I was hoping to be able to hook up a switch to only use when my GP's fail to ever come on.

I do like the idea of having a switch for disconnecting the juice to the GP's if they fail to GO OFF.

I thought the controller was on the back of the motor, and the picture above is the solenoid right?

 

Every one is talking about going to a solid state system. What is all involved in converting?

Is this the Relay I need?

eBay Motors: Motorcraft Glow Plug Relay 88-94 Ford 7.3 Diesel IDI (item 260211319348 end time Jan-07-09 04:51:04 PST)

What else needs to be changed to go solid state?

 

That is the new style controller/relay.
You would need a little change in the wiring to make it work.

Here is where it gets a little funny.
By all logical reasoning you should be able to locate the solid state controller where your existing relay is, and just change a few wires.
And by logic, the ZD 1A glow plugs should work with it just fine.

I do think I have heard of the cycle times being off with ZD 1A glow plugs though.

If that is the case, you would have to change the terminal ends on the glow plug harness and change the glow plugs to ZD 9 to make it work right.

Sounds like he had cut one of the wires on the controller and spliced a momentary switch in so the glow plugs could not come on.
That is what I have done, but I did it at the relay so you could go manual override.

I don't know how long you were shopping, but the temp sensor on the old style controller will not turn the glow plugs on when the engine is warm.
Even at temps in the 20's you may not need glow plugs two hours or more after you shut the engine off, the heat left in the block is more than enough to fire it off.

 

I tried to start it and the GP light would not come on, the temp was about 140 still. I was able to finally get the GP to come on after sitting a little longer and it fired right up. I think having that back up push button will add some security for me, with worrying about will it start or not.

Actually he didnt cut any wires at all he just added I believe it was two wires to the GP controller and ran them into the cab. I removed the switch and wires when I replaced the bad ignition with a working one and the GP's worked off it without having to wire anything, so I really dont have a clue to what he did cause it was over a year ago.

I was hoping I could just change the Terminal ends to the bullet style instead of changing the whole harness, because aint the main plug in an 8 pin and the newer one a ten? Or something like that...

 

That is correct.
If you use the new style harness you will have to splice wires to make it work on 86 and older trucks.



The wires at the glow plug controller go directly into the controller connector.
Easiest place to disable the automatic controller is at the relay.