Welp I found a shop in town, that carried the ZD9's reasonable and picked em up, seems i was wrong in my assumptions tho, all tho im getting the volatage to the plugs looks like something other than the plugs is causing the system to be engaged for a useless 1,1/2 seconds rather than full proper glow time. Back to the drawing board and checking wiring, Not too worried as i only paid 80bux even of the plugs and wanted to replace the Crapolites that were in there anyway. Figure while i'm in there might as well fix it all CORRECTLY. Thx guys

 

Ok just to make sure I rechecked Voltage coming to all 8 GPs. The voltage is there. Are there any tests I can run to check and see if the Relay/Solenoid is bad or if the controller is bad. I'm getting voltage to the GPs. Problem is the power is only there for about 1,1/2 seconds not 10-15. My wait to start light only flashes on and off and then i watch the Voltmeter on the dash drop and return to 12v etc after about 1,1/2 sec. I'm wondering if that solenoid could be bad in some way, when it hits a certain voltage/amp draw it closes its circut. which I would think would cause the controller to think No GP's are present i.e. my short or almost non-existant WTS light. Thinkin out loud again any ideas would be great. thanks

 

my opinion is that there is nothing at all wrong with your glow plug system other than the fact that you have autocrap plugs in it that are burnt out.
i bet once you put the ZD-9's in the engine, it will fire rite up and work properly.

 

X2 WTS Light will not come on for required time (usually 10 seconds) if the controller doesn't "sense" there are good glowplugs.

 

You said you got Motorcraft plugs, but you did not say you changed them.

So at this point it looks like you turn on a switch and send power to a burnt out light bulb.
Even though you are getting power to the bulb, it still will not light until you change the bulb.

If you did change the glow plugs, you need to find the connector where the engine harness plugs into the chassis harness.
Two wires in that connector carry current to the glow plug relay.
If there is any corrosion, the current may be lower than what the controller is expecting, and alter the glow timing.

 

Well I looked into how the system operates and it seems through a serious of fancy procedures telling it when to and when not to engage, the glow plug controller is a glorified switch completing the circuit to fire off the glow plugs by creating a ground. To see if the solenoid and everything worked, i had my gf turn the key on in the truck while i checked the power going to the glow plugs, 9.6v which lasted about 1,1/2 seconds or so, which i already knew from testing earlier. This time i rigged it so i could take my hands off it. This time I ran a ground from the negative post of a batt to the groud lug on the solenoid/GP controller relay. This was the on the left side closest to you, if your are looking at if FROM the FRONT of your truck. It is yellow in my case, ive read it could also by white. Once I hooked up this ground I got my voltage back to my GP's, until I removed it. Now unless im mistaken this tells me my controller is bad. Scince I cannot afford a new controller it looks like i'll be bypassing it with a 25amp momenary switch in the cab. Thanks guys for the help

 

that tells me you have bad ground

 

yup. nothing wrong with the controller other than a bad ground connection.

 

How the system works.

The nominal glow plug resistance is .5 ohms for each glow plug.

So the controller senses the resistance of the glow plug circuit, which twlls the controller how hot the glow plugs are through the changing resistance value of that circuit.

As glow plugs get old, the resistance increases.
As glow plugs get hot, the resistance increases.
If glow plugs are burnt out, the resistance of the circuit changes.
If the power supply has corrosion in the engine harness to chassis harness connector, the resistance changes.
If the glow plug controller ground is not making a good connection, the resistance changes.

When the resistance changes a specified amount, the controller shuts the glow plugs off.

Sounds to me like you have one or two burnt out glow plugs, of several glow plugs that the resistance is outside the optimum value, .5 to 1 ohm.

So the controller is doing exactly what it is supposed to do, shut the glow plugs off when the resistance changes to a specified value.

Now consider when you have a couple burnt out glow plugs, the power they should be using is going to be split between the remaining good glow plugs.
So they are going to get hot faster than normal.
Next thing you know, all of them are burnt out, and you can hold that manual switch as long as you want, the engine will not start.

And the yellow wire should be on the power out to the glow plugs terminal of the relay.



200 amps draw when heating the glow plugs, so that 25 amp switch will be smoking.