1984 6.9 IDI Wiring diagram or harness explanation?

[Coco]

hey everyone, hope you’re doing well! i recently switched my 6.9 IDI glow plug harness for a 6.0 Powerstroke harness. i did the 7.3 idi glow plug system conversion, which worked, it has 7.3 plugs and relay, however when i gutted the original glow plug harness to clean up the engine bay i must’ve cut the wrong wire somewhere because i have no power to my cab. custom wired courtesy lights, dash, headlights, cargo/dome lights all did nothing. batteries are brand new, and their grounds were JUST cleaned when i did my lift pump.
the only wires i removed were the 2 orange 10 gauge wires that split off to each plug. the bullet connectors i originally used for the conversion loosened up and started popping off the plugs anytime they were touched by something else which is what opted the 6.0 harness in the first place. and it looks amazing in the engine lol

i did try following the wires to see where they go, but can’t find anything beyond the plug. the two orange wires disappear and go into 6 or 7 other wires that all route past the A/C stuff on the passenger side into the firewall. if those orange wires ARE the power feed to the cab harness, then where should i connect them? i can’t remember if/where they were on the 7.3 GP, because the 6.0 harness has its own wires to get the signal from. any help is greatly appreciated!!

[Ford F834]

Hi, I’m not quite sure what you cut or disconnected in the process of converting to the 7.3 glow plug system or 6.0 harness, but here is a link to the 1985 EVTM for diesel glow plug system:

https://www.garysgaragemahal.com/start--glow-plug-controlrun-diesel.html

That should be pretty close to what was originally there on your 1984.

And here are a couple diagrams from a 1990(?) era 7.3 glow plug harness:





Hopefully this should help you make sense of the wires in front of you. If everything looks properly connected, check to make sure none of your fusible links are burnt.

[Coco]

those diagrams are a godsend bro, that explains a lot!!
i believe the wires i cut were the “Battery Feed” terminal on the engine harness. 10 gauge orange wire, bottom left corner in the photo. that would probably explain why i randomly lost power AFTER screwing with the wiring 🤦‍♂️
i’ll try and get some photos of my truck when i get home; but from what i’ve seen and the diagram it looks like that’s the culprit (hopefully).
my next question is, if i cut the battery feed wire, where does it need to go? on the relay or straight to battery? it has been a while since my truck had the original glow plug relay, and when it did i was not messing with it lol so i don’t remember the factory routing and everything

[Coco]

those are the two wires i removed when i did gutted the factory harness. i also shortened the two wires on the opposite side of the plug which were on the relay as well but i don’t remember where they went or what they controlled

[85lebaront2]

Ok, I have the glow plug wiring for the 1984 IDI engine in my AllData.

[Gary Lewis]

Bill - Send them to me and I’ll add them.

[85lebaront2]

Ok, coming to you sir!

[Ford F834]

The cut orange wires supply power to the glow plugs. The feeds on the female side of that connector terminate on the switched lug of the glow plug relay.

So how are you powering the glow plugs if not from the pair of orange wires?

Regardless, I will trust that you have your 7.3 GP conversion figured out since you say it is working…

The lack of cab power is a separate issue. My ‘86 IDI cab power comes from the starter relay lug. The wire is black with an orange tracer, but there is a 6” piece of light blue fusible link at the end where it connects to the relay. The union molding says “fusible link 14 GA”. I suspect this could be your culprit. Check to make sure you have a good connection at the relay lug, and use a test probe to pierce the insulation on the black/orange wire and fuse link to see where you are loosing power. The fuse link may be fried or have a bad connection.

[Ford F834]

You will want to look at this

https://www.garysgaragemahal.com/charge--power-distribution---diesel-engines.html

[Coco]

ahhh, okay so i was originally right when i removed them. the new 6.0 harness had a female 4 terminal plug that i cut off, and crimped each set to a 10ga wire and ran to the relay. part of the goal is to make my engine bay as clean and tidy as possible to make work easier (and so i can flex on my friends lol).
 

the fuseable links all feel very old—i’d expect so from a 40 year old truck lol, would it hurt to replace them with modern fuse links? i work at “o’reallys” so they’re pretty cheap, and easier to replace should it blow later

i will try to get out there tomorrow morning before work, and look at the terminals; just double check everything using the diagrams that were posted earlier.
thanks for your help with that, i’ve been running around circles for days now trying to figure out how glow plug power feed wires could have possibly messed up my cab power. there’s a reason i only like wiring light bars and speakers 😂😂

[Coco]

oh my, these are very nice!! i’ll admit i’m pretty terrible at navigating forums and sites without my computer, my phone is too small lol. these links are much easier!