How to Un-Wire a Frankenjeep

I'm going to have the dash out of my 74/76 Frankenjeep this weekend and I thought it would be a good time to clean up the mess of wiring under it. There are numerous wires that are not connected and hanging loose. I bought a Craftsman auto circuit tester, but I have no experience with auto wiring other than installing a couple of tape players back in high school. Could anyone give me a simple primer on how to go about determining what wires should stay and what should go? Thanks.

 

The first thing to determine - do you have a '74 or '76 wiring harness? They will be completely different. The '74 harness uses fuses inline with the harness, and the '76 harness has a fuse box under the dash. Then you need a wiring diagram for the year you have. This can be found in the factory manual for the appropriate year. Then you just trace out all the loose wires. It should be fairly obvious which wires were factory installed and which were owner installed. Anything from the factory should stay, all else goes.

 

Tim, as always, thanks for your help. A couple of very basic follow-up questions: what do you mean by "fuses inline with the harness"? By tracing the loose wires, do you mean just mechanically tracing them, or do you mean using a tester of some sort? Thanks again.

 

Do you know what an inline fuse holder looks like? It has two plastic halves that twist together with a bayonet mount. The fuse goes inside it. If that does not ring a bell, I'll see if I can find or make a pic.

First mechanically, then electrically when you can't follow any more. The earlier harnesses (ie '74?) were wrapped in tape, making mechanical tracing harder. Later harnesses use split plastic loom, which can be opened like a pea pod to see inside.

 

Got it. Thanks again.

 

Tim, if you are still out there - my worst fear became realized when I went out and looked under the dash. I've got a fuse box on the firewall (interior side) to the left of the steering column, BUT I've also got several wires with inline fuse holders in them. The harness appears to be taped together (actually there are two big gobs of wires that come together under the dash that are taped together). :?

 

yup... it will be easier and you'll be a lot happier with it when its done.
when i get around to buying gauges for my flattie im going rewire the whole rig.

 

That's what I was thinking - a new harness - but given my lack of knowledge re auto wiring I didn't know whether to even let my mind go there. Here is the progression of my project scope creep (there's a question at the end of this): My roll cage bolts into my dash. The roll cage is unfinished and is scheduled for a powder coat next week. While the cage is unbolted from the dash I was gonna install new custom fabbed stainless dash. While old dash was off was gonna clean up globby wiring under the dash. I don't want to leave jeep undriveable for more than few days because our season is quite short here in Big Sky Country. So, question is: if I go ahead and install new dash now, can I put a new wiring harness in later without taking dash out (and therefore roll cage)? This made me tired just typing it.

 

{shrug}
is everything working okay, gauges, lights, etc ?
just tape the loose ends up and add tie straps to clean things up.
why replace/rewire if not needed ?
there were lots of unused/extra wire ends from the factory.

 

I rewired my very first jeep (1947 CJ-2A with a chevy 327 stuffed in) back in high school. NO electrical knowledge before, no 'father figure' to 'help'. Did it myself with a bunch of studying (this was pre-internet) and just plain 'figuring it out'.
If I did it, you can do it....
PS get a GOOD wiring diagram...

 

You will be MUCH Happier with a new harness. The extra bucks will save you much frustratuion and also give you confidence in your rig's new wiring.

 

New wiring gives you a lot of peace of mind. You'll know the wiring harness front to back for troublshooting and upgrages later. Everything works better and and the light are brighter. Not that difficult as most kits have wires marked every few inches and less frustrating than chasing down old wires.
When I did mine I had inline fuses, random loose, stiff wires with bad connections and grounds. Some wires will oxidize black inside the insulation for several inches and you won't know it. A lot of wires were rubbed thru and shorted intermittedly or just burned.
Very satifying results to rewire and not terribly difficult.

 

The hardest part is the turn signal switch but with the help of these fine folks you can overcome! It can be done with the dash in place but is more difficult. I've found removing the driver's seat for more room to move made a huge difference for me. I'm fairly short but kind of bulky. I'd agree with replacing the wiring harness with new but if that's not an option then repair what you've got. Take your time, spend plenty of time with a good wiring diagram, and ask questions when confused or stumped. If you take it one step at a time and one circuit at a time there will be tremendous satisfaction when done and you will be that much more familiar with your Jeep when it comes time to trouble shooting issues down the road. Make sure all wiring is insulated and secured so it can't rub and short out.