On my last two trucks I installed a cut out (cut off) switch so you don't have to run the GP's all the time. I get tired of the GP's running all the time just when I move the truck or anything else where you have to turn the key on. Anyway, I can't remember which one of the little wires you splice into for a toggle switch? I think one has power all the time and the other doesn't and is used by the PCM to go to ground to activate the GP's. So, what one do you think?

 

Glenn,

Turns out that I've just been wiring my efuel system so I've been studying and working with the wiring in that area. The red wire is always hot when the key is on. The purple wire is the wire that gets grounded by the PCM to turn on the glow plugs. I didn't splice into mine. I disconnected and insulated the purple wire that the PCM grounds out and replaced it with a wire going to my new manual switch on the dash. So, the manual momentary contact switch does the grounding instead of the PCM.

Here's a thread:
https://www.ford-trucks.com/forums/1...with-pics.html


This mod was one of the best things I've done for my truck.

 

Thanks Bob, just because I don't have a memory anymore doesn't mean I couldn't have use the search! Reps sent!

 

Hi Glenn, I waved at you a few weeks ago coming back from Phoenix. Well, actually I waved at the Lake Havasu exit off of I-40.

I would use the ground wire in the toggle switch. Reasoning here is if you used the power wire and sometime in the future the wire shorted to ground it would blow fuse #22.

 

Thanks Jim! I saw you and waved back, LOL. Reps sent!

 

Not that I've done this yet, but if you use a single pole double throw (SPDT) switch, you could run the ground wire from the relay to the center; then on one side wire the ECU ground wire; on the other side wire a grounded push button/momentary switch. Then you can flip the toggle to position 1 and let ECU run the GPs normally, or flip to position 2 and run them manually with the push button.

 

Best of both worlds. That option would be useful if your wife uses the truck and doesn't want to have to mess with manual switches.