Harness Making Tips & Tricks

I was hoping this thread would take off when Gary first started it, but it appears to have died away...

I'm planning on customizing my harness with a kit from Painless(10103). I just called them and the guy I spoke with seemed to think I was crazy or very brave/stupid, but of course still very willing to sell it to me. Do I need a 'Phd' in wiring harnesses to attempt this, or is a couple of wiring diagrams and some determination sufficient?

I helped a friend use one of their kits on a 1955 Dodge pickup he was building. They are not a bad kit if you like GM products. We ran into a number of minor issues as he wanted to stay all Mopar (360 V8, Torqueflite etc.) He had a nice Chrysler alternator and a Mopar performance electronic ignition. None of the engine connections worked as designed. Gauges were another fun piece along with Heater and AC.

I rewired my truck and am in the process of doing the same on my 1986 Chrysler. I was not going the buy a wiring "kit" that will not include connections for any of the pieces I am using (SBEC, Imperial ATC system etc.) I will post some of it after dinner.

No, you don't need a Phd in wiring.  You just need to be thorough and organized.

X💯!

And, you need to be the electron, 

Shocking, Jim, shocking.

The very first thing is to decide what you want to do, bigger alternator, maybe go to EFI, additional lights, snow plow, winch or what ever you plan on doing. Next is to have a place to do it, if you can lay everything out the way you want it, the job will be easier. The factories have, or at least had what was a big mockup of the harness layout with the components located, starter relay, lights, ignition system etc.

On the 1980-86 trucks the entire front harness is one piece, from headlight to headlight, and passes through the firewall twice, once under the heater or AC casing and the other near the power brake. Starting in 1987 Ford went to a round 53 pin connector on the left side that everything in or out through the firewall runs through. 1980-86 the rear chassis harness plugs in near the bottom of the left inner fender, this was kept in 1987 and possibly through 1989. In 1992 Ford changed to a 76 pin rectangular plug for the front harness and a smaller 24 pin one for the rear harness.

Alternators, 1980-86 used two different alternators, a 1G with a separate regulator and a 2G with an integral regulator. The 1G has studs, the 2G has a pair of plugs, the larger of which is a problem. A 3G conversion is an excellent idea, but the ammeter will not handle the higher output.

Ignition switch, the 1980-86 and the 1987-91 switches are similar, but have different plugs, but are physically interchangeable. 1992-96/7, the whole column is completely different.

If you are just trying to repair a damaged harness, you need at a minimum the EVTM (Electrical and Vacuum Troubleshooting Manual) for the year you are working on. DO NOT RELY ON AN AFTERMARKET MANUAL! it will bite you on the posterior. If you plan on doing major work and will have the dash out, I would recommend taking the wiring harness out so you can get at everything like this one, this is a Chrysler Lebaron front harness.

If you mark and then locate the turns and components along with plugs you can do a much better job with it out in the open. The split plastic loom that Detroit loves can be bought aftermarket. It is recommended as taped areas if they aren't exactly right will not bend nor go where you want them to.

I cut, strip then twist together, solder and heat shrink mine, one problem I ran into on the Chrysler, their ground cable is part of the harness and only serviced as an assembly, Ford did a similar system on their newer vehicles, but usually just the positive and negative to the starter are done that way. In order to get the ground cable I needed for my Chrysler, I had to make one as I will not use the clamp-on battery cable ends.



I soldered the large cable by first wrapping it with some smaller wire after mating the larger wires then used a propane torch to melt and flow the solder. I was able to find some larger heat shrink to put over the splice, then filled the small gaps with RTV to weather proof it.

A suggestion Bill.
If you're not ok with using a military style battery terminal (NOT one of those crap 'emergency style' clamping ones) consider running your ground cable out to the battery.
Terminate it with a tinned copper lug, and put it under the battery terminal's clamping nut.

I've done this on my positive side, as the newer Ford lead free cable doesn't really have enough slack to cut it off and change it.

Jim, I have used them (readily available here) but there is limited space underhood on the older FWD Chrysler products (even the battery is an odd size). I actually did the solder-on lug for the starter cable as the Sebring PDC I am using has a large + stud on it (Sebring battery sits in front of the LF wheel under the fender and both cables come up to M10X1.5 studs for access.