Alright, so my wiring is not that handy, but i can get it done if i know how to do it right. I need to wire in a 10ga. or bigger key on hot to run my glow plugs and injector pump. Ive been running just the IP off of a now unused ignition key on wire (14 or 16ga) and now im having problems with it. The reason i only ran the IP and not GP and IP was it seemingly didnt have enough power to run both. IE glow plug circuit got power, but not enough to close the solenoid, and the fuel cutoff solenoid didnt seem to work right sometimes.

So any help to do this the right way would be appreciated.

 

Here's the general idea of what you want to accomplish:



If you're drawing enough current to require 10 gauge, you'll want to keep that out of the switch; so you'll need to use a relay as shown in the schematic. Run the 10-gauge wire off the battery side of the starter solenoid using a ring terminal, and place an inline fuse close to the solenoid. The wire then runs out to the relay. The other side of the relay contacts go to your load (it's shown in the schematic as a terminal block).

The only load you add to the ignition switch itself is the relay coil, which is a very light load. Make sure you pick a relay that is rated higher than the total current you're drawing, with ample margin. I personally would use a relay with contacts rated for 150% of the current you'll put through them, if you can find it.

Just a side note - I don't have a lot of experience with diesel engines, so it'd be nice if someone who does can also chime in to make sure 10 gauge is large enough for the application (10 gauge is quite large, but I don't know how much everything you're talking about actually draws).

 

I really appreciate such detailed help. The line i need to add runs the fuel cutoff solenoid, with is almost nothing, the cold advance / high idle, and the glow plug relay, which is basically a starter solenoid. So i dont know how much current is required, but the wire in the engine existing diesel harness is 10ga.

So my next question, how do i hook into the switch? IIRC i added one by soldering into a blk w/org wire at the block through a fuse for my other hot point. I may look into rerouting that for this application. In hind sight, a key one power point has its limits. I need to find how this is wired factory. I dont like the idea of blowin a fuse when the glow plugs cycle (everytime you start, hot or cold) and being stuck in the water without a spare. Oh, and for obvious reasons the wire for the IP / GP has to be hot @ key on, and crank, but not ACC. If anyone knows which wire to tap into, that would be great. Trying to do this as "factory" as possible if you get me.

 

I got to thinking, the ignition wire i was origionaly using to supply power to the engine should surely work to operate the solenoid. So all i need now is a solenoid rated for whatever 10ga. is rated for, or as you said a little higher to be on the safe side. I might need to check the wire though, i never thought about it, but it might not be a full 12v, although im pretty sure i have at least 1 more unused key on hot under the hood. This should all work pretty well, i was planning on moving the glow plug controller to the inner fender anyway, but it might go on the firewall. I dont want it where it sets on the back of the engine, but i cant go too far because i dont want problems with the actual glowplug wires themselves, and i dont want to have to rewire them to a larger gauge.

Also, this new solenoid i should end up getting, i wonder if its something i can snag at the JY, or if i buy it new, anyone know what they run?
Maybe i should ask in the diesel forum just where this solenoid is, and grab it off that truck along with the plug and any wires that come with it.