Is there any way to test a gp controller without the relay? And does anyone have a wiring diagram for the controller/relay setup?

Thanks, Jeremy

 

https://www.ford-trucks.com/user_gal...oid=74195&.jpg

One picture is worth a thousand words.
This one is of the relay though.
The black wire must be grounded to a good ground on the engine.
The ignition terminal is always hot when the key is in the on position.
The battery terminal is always hot.
The glow plug terminal is hot when the glow plugs are heating, this terminal also has the yellow wire and the green wire (hooked in different places) to regulate the plugs heating time.
The controller causes the white wire to go low (to ground) to energise the relay.

Very easy to hook a wire to this white wire terminal and to a push button that goes to ground to make manual control glow plugs.

 

Thanks for the help thats a good diagram.
Jeremy

 

I don't understand the description of the glow plug terminal connector. It says "this terminal also has the yellow wire and the gren wire..."

Does that mean this terminal is part of the control circuit or does it provide the path to the glow plugs for power when heating them? I don't understand how it could regulate the heating time and provide the power to the plugs?

I'm having trouble in this area too, and trying to learn all I can about this thing before I dig in.

Tks,

 

I don't really know how it works either other than it is a timer for the GP, but it does somehow sense heat and turn off at different temps depending on the engine temp.
Jeremy

 

There is a resistor built into the relay connectors.
It is the S looking thing in the glow plug out side of the relay.
That and the resistance feedback from the plugs themselves is what "times" the heat cycle.

The yellow wire is on the relay power out terminal.
The green wire is on the terminal where the glow plug harness connects to the relay.
Only two inches difference of position in the same circuit leg.

I can not tell you exactly how it works, when it starts out the current is not even on both wires, but the rising resistance increases the current level on one wire to balance the other wire and the relay opens when that happens.
I am not even sure it balances, but it does reach a pre determined level in relation to the other wire.

 

Sounds pretty complicated to me why cant they just put a timer on it.
Jeremy

 

The time the glow plugs stay on at 40 degrees is not the same as it is at 20 below.

The resistance feedback was the easiest way for that to happen correctly.

 

Ok thanks it makes sense now.
Jeremy

 

Man, that's weird science! I've got another question but I don't want to hijack JBOARD'S thread, so I'll start another one.

Tks