As I continue tearing into my truck's wiring I'm starting to better understand why the changes that were done were made. Still no idea why they were done poorly, but I've got another thread about that. One of the wires (38A on the 1971 wiring diagram) running into the starter solenoid has completely crumbled inside the insulation and was bypassed when the ignition toggle and push button were installed. I suspect it was the reason the toggle was installed. I've got no idea what condition the rest of the harness is in, but I'm seriously contemplating replacing the entire wiring harness as I'm kind of electrically clueless and this would prevent lots of potential future headaches. The major down side is that I'd have to figure out how to wire the mystery alternator and old Mallory ignition system. I can keep plugging away at the existing wiring, but if it isn't a big deal to put in a new harness I might rather put my time into that. What do you guys think? Anyone replaced a harness? How hard was it, and is it worth it to keep trying to repair the one that is already in the truck?

I'm sure most EB owners have stories of how a PO has hacked an install of parts critical to the safe operation of our trucks. When I purchased mine a PO had had the headlight buckets cut out of the front clip and buckets for dual rectangular chebby welded in. the wiring was spliced to the extra headlight with U-haul type splices that caused the headlights to go out at times just by hitting a bump in the road. The PO's son had also installed a stereo and amp with cut harness wires hanging free behind the dash. It looked like a dash fire waiting to start at any time. All that said to tell you that with the condition of the harness in yours, IMO, you would be better off replacing the whole thing. I replaced mine with a Centech BR-10A harness. Others have used a Painless harness with the same result, a harness with new wire and no hidden gremlins from a PO's attempt at improving/changing/adding things. The installation was not hard but it does take more time than Centech says to do a clean install. I soldered/heat shrinked all connections instead of just crimping as well as a few other modifications to make it more Ford plug friendly. You also need to read the instructions until you understand them completely. Once the install was complete I've had no issues and as a bonus everything works like it is supposed to.
Happy New Year, .... Mark

Thanks! Just out of curiosity, what mods did you make?

I'm going to second 71 Broncoman on this.

If this is a truck you plan to keep for the long haul, a new harness is in order. I never did a new harness on my 66 or 69. The 66 was simply a work in progress that never progressed. The 69 was never a Bronco I told myself I was going to keep forever. The 72 is THE Bronco though. And as such, all the wiring is coming out and a new harness is going in.

As far as Centech versus Painless goes, I've heard pros and cons for each. I am planning to go with a Centech, when I get to that point, because I have heard the majority of positive feedback on that kit. The way I look at it, I want to knock out any and all wiring issues possible in one move so I can progress on to other, bigger and better things.

I put the centech in my 74. Great kit. I would use the kit again if I got another bronco.

Thanks for the feedback! I'll likely be ordering a Centech harness today or tomorrow. Seems like cheap insurance against future problems.

The mod's I can think of right now are; On the Centech instructions you would cut the Ford plug end off all the lights and install weathertight connectors to the light socket wires. I made pigtails with the weathertight connectors and the ford plugs so the OE light plugs are intact so it will just be a plug and play if any of the lights get damaged/ripped off for some reason. I also had to lengthen some of the wires in the engine bay to be able to route them cleanly around the fire wall and up the left side of the heads like the OE harness. The wires going to the coil would have to have been routed over the pass. side headers (not good) just as an example. I also used split loom or friction tape on any unprotected wire bundles both in the engine bay as well as running to the rear. At the same time I installed a Pertronix, which bypasses the ballast, but I kept all the wires for that intact as well as a set of points in the tool box. I used quite a few rubber coated SS clamps to keep the wires/ loom from pinch points, wear points, and sources of high heat. I even used heat sleeve on the rear wires where they were around the exhaust system. Some of this may seem like overkill/anal but, I just like to "do it once, do it right", and everything works fine.
Hope this helps, Mark