Hey all, I have a 85 Ford with the 6.9 diesel with major wire issues. At one time a harness was burned and now the issues are numerous. I bought the truck as is thinking it could be a easy fix, but not looking so easy. My latest idea is to "build" a dash setup and rewire the whole thing. I have a service book for Ford trucks, and have been studying the wiring, (however none seem to be diesel diagrams)  and a lot of it seems simple, but wondering if anyone has "rewired" one of these before, and wondering where I should start as far as doing the engine, as it starts and runs ok still, it just has no lights, heat, wipers, etc, and I'd hate to cut or rewire something and have a bigger problem. Any help would be appreciated, as this is my starting point on the project.

Thanks in advance,

 Brad  

2500 dollar harness,try painless wiring..  

the 85 only needs basics to operate,
altenator, starter, power wire for the pump fuel shut off, tps sensor for the auto OD if it has one. and a glow plug relay. the glow plug relay is as simple as wireing up a set of new fog lights.  

Glow plug wiring is not quite as simple as fog lights in that it draws considerable current and heavy wire with good connections and proper fusing is needed or it can "burn up" again.  

it is as simple and yes it draws much more juice and requires heavy wire..and relays  

Ok, so as far as the glow plugs, I don't plan to "cheap" on them, or anything else for the matter. I usually play with old tractors, and this would be my first truck project like this. I guess I should say that the ignition starts/stops the engine, but still have to jump the glow plugs. I don't know if this would be due to a bad timer, or if it is due to the same reason that nothing else is working. (the harness on the right side of the truck is the one that burnt) The only other electrical that is currently working is the brake lights and headlights. (No running lights, front blinkers, dash lights, heat..) All circuits have power at the fuse box, but don't have power at any of the plugs. I was thinking bad ground, but even if I ground my test light to somewhere I know I am getting a good ground, still same results.
I guess what I really was asking is if anyone has done this that maybe could walk me through the rewire process, as I want it to still start/run when I am done, be dependable, and not really worry about the truck just stopping because I did something stupid.

 Thanks,

 Brad  

it's likely the relay/timer is the cause of the failing glow plugs, that was/is a common problem, in the early years it was cost effective to put a switch and starter reay in to operate the glow plugs on the factory wireing, you just had ot shut them off before they burnt out. now the new updated plugs don't just burn out..  

You are going to want at least 6 ga wiring on the glow plug circuit main feed. YOu could use 4 but it is not really needed for this. If the feeds for individual plugs split out from main feed, 12 ga would work to feed one plug but 10 ga will give you a bit less voltage drop and more even heat on all the plugs. Where you want to spend some coin on heat is not extra wire size but wire with high temp insulation on it, not normal 85 or 105C rated soft stuff.
FEP Teflon insulated wire would be a good choice here as it is abrasion and moisture resistant and good to 204C (400F) continuous and intermittent to 260C/500F. Glass braid insulation is good to 900F continuous and 1000F intermittent but lower abrasion and moisture resistant. TFE (teflon taped glass braid) would be best to use here as it has same temp range as glass braid but excellent abrasion and moisture resistance too.  

Any recommendations where I can come up with a schematic to begin the wiring process? The lights seem cut and dry, as my plan is to run a power wire to my cab (something heavy) and get a fuse block from say napa, and branch off my block to run the headlights, wipers, etc. (branch power to my light switch, wiper switch, so on) I am thinking since the engine side harness isn't burnt, I will leave it as it is (other than glow plug function, which probably is in the right side harness anyhow)I guess my whole thing is, although not a primary driver, I will be doing some street driving with it, as well as one of my projects to goof around with. As I had mentioned before, I am actively considering removing the factory dash and fabricating my own. Should I end up following through, would be really nice to wire it myself and put it all where it can be easily accessed in the instance of adding more lights or other features. This would be my first custom thing, and although the truck is slightly rough, I do have a clean body that could end up on this chassis someday, so I am playing with something rough to come up with something I like to put in the finish product, that way should I not like it, I didn't hurt something good.. (and I like the looks of the custom dashes with aftermarket gauges I've saw..)

(Guess I should add that I have a service book, but all of the wiring schematics seem to be for gassers. I know that chassis electric would be the same, but the diesel would be different, right? possibly uses the same plug ins, but the wires go to other places? also know there are other wires for other functions...  )

 Thanks Again,
 Brad