This project actually took me a couple of months to complete - the date on this article is when I started.  It took awhile for a few reasons - I made the job more complex, I was picky about the connections, and at some points (like the underdash work) I could only do a bit at a time before I was just too sore. 

At any rate - here is a project wrap-up on re-wiring the entire Jeep.

The wiring harness I used was a 21-circuit version from EZ Wiring.  I ordered it directly at a cost of around $175 (it looks like the prices have gone up a bit since).  I needed more than the basic 12 circuit version as I’ve added a number of auxiliary lights and accessories to SSDutch.

I started as per the instructions included in the kit.  The instructions aren’t bad, but aren’t great either - a bit of effort with a digital camera, a technical writer and spell-checker would do wonders - however overall I’m still happy with the kit.

The first step is to lay out the harness on the floor, then grab a camp chair and take turns staring at it, then at the Jeep:

The main goal of this step is to reconfigure the harness - which makes some assumptions about location of different items - to work for the Jeep.  Each main group (rear, dash, engine) will need to be resorted for the Jeep application.

Then it’s on to mounting the main fusebox.  I choose the traditional location of under the driver’s side of the dash:

From there it’s on to routing the main wire groups.  I chose to route the rear group through the interior of the Jeep for a few reasons:

I had a couple of wires to run down that way anyway - for the underseat water pump and the light I have mounted on the side in the rear.

I liked the idea of having wires up and out of mud/water/snow/sand and away from tree branches etc.

Plus when I looked at running them out the firewall and back under, there’s so much stuff right in that spot—brakes, clutch linkage, exhaust etc that I didn’t want to add more complexity to that space.

So here’s how the rear wire group is routed:

I worked from the rear of the Jeep forward - so once the wires were routed connected the rear taillights, backup lights and my rear utility panel that houses both a power plug and a connector for my trailer lights: 

I tested the circuits by using a 12v battery charger - attaching it to the main power wire of the wire harness.  If you try this note that there are a couple of parts of the fuse block that are intended to be powered up by the ignition switch - so you’ll have to find those and apply power to them as well.  Once all the circuits were confirmed I used spiral wrap from Radio Shack to make all the wires look neat.

Since I didn’t have room for one on the dash, I added a 12V plug in between the seats:

It locates nicely by the rollcage “belts” that I put in for attaching holsters and cases for cell phones, digital cameras and GPS units.

Once the rear stuff was done I moved to the dash and installed all the gauges and the steering column:

Note that I had to install all of this in the Jeep - I couldn’t remove my rollcage, which meant I couldn’t really wire the dash outside of the Jeep then install it once wired.  I got lucky though - I found that I could lay sideways through the door opening, with my feet on the wall, and not be terribly uncomfortable.  I couldn’t work all day like that - but it was better than laying completely in the Jeep.

From there I moved to the main switch panel - which I wanted to take the place of all the stock switches for headlights, wipers, etc.  The panel is an aftermarket unit that came with fuses below the switches - visible here in the early stages of laying out the dash:

With the new harness I didn’t need the fuses, so I solved the issue of both getting rid of the fuses, covering the holes they left, and labeling the switches by having some engraved labels made locally.  After painting the panel to match the dash, and installing all the switches, lights and fuses it looks like this:

The aux circuit will turn on a rear offroading light I plan to make.  The “idle up” will, once I have the fuel injection installed, tell the computer that I just turned on the A/C, which will bump the idle speed up for use with my onboard air.

Here is the panel installed in the dash:

Note that there are three specialty switches here that I bought online from a supplier for the dune buggy crowd - the first is an off/on/momentary that handles both turning on the ignition and firing the starter.  The second is an off/on/on that handles both the parking lights and headlights.  The middle is an on/off/on that handles the wipers - both low speed and high.  All three of these switches are sand-sealed for protection.

So here’s the conundrum with this approach - do you route all the high-current circuits directly to these switches, or do you pair up these switches with relays that actually handle the high-current switching?  I chose to go the relay route - both to keep the thicker, high current wires all under the hood (there turned out to be *very* tight clearance behind the switch panel as the defrost duct for the heater is right there), and in an effort to get brighter lights (I’ve often read that using relays with headlights makes them brighter as they are not being switched by a lower-quality headlight switch).

This decision required two things then—a place to mount all the relays, and an auxiliary fuse block to provide fused power for the switches themselves, leaving the fuses in the main EZ-Wire block in the main circuits.

I decided to mount all the relays on the top of the drivers side fender.  This may not be a great place for everyone - but I don’t do mud and very little deep water so I think it’ll be ok.  However - I wanted to be able to swap out the fender without having to deal with all the relays and wiring, so I used a piece of thick strap steel that mounts to the fender with two bolts:

Oh - somewhere in all of this I also bought a terminal strip from Radio Shack, along with the little strip that goes in one side to short all the connections together into a common one - and used this for a common ground point up under the dash:

The heavy green wire connects the block to its own mounting screw, and on the backside (engine side) of that screw there is a heavy gauge ground wire running to the spot where the battery ground strap is attached to the alternator mount.

OK - back to the switches, lights, and relays.

I started with the parking lights and headlights.  I used another of the Radio Shack strips for the parking lights - so the one red wire coming from the relay in this picture lights up the four separate wires to the individual parking lights:

Note that with the setup, the parking lights now stay on with the headlights—something early Jeeps didn’t do originally:

Then I moved to the turn signals and hazard lights. To make the hazard lights work I ended up tapping in the above 4 turn sigal circuits, but using diodes between the hazard light wire and the turn signal wires such that when the turn signals were working they couldn’t backfeed to the hazard light connection and fire all 4 turn signals.

I did a quick restoration on the Sparton turn signal:

Much credit goes to David Hoelzeman and his online rebuild guide for the unit.

The only gotcha I had was soaking the unit in PBBlaster softened up the little green lens over the light to the point of not being able to use it.  Even though I’ll have signal lights in the intermediate-era replacement speedometer, I wanted a green lense to fill the hole in the turn signal unit.  I also replaced the wire housing with a chunk of 5/8” vacuum hose.  It’s a bit thicker than the original but should work fine.

I ended up just cutting a piece of a baking soda container lid, and duct-taping it into place:

I also want to record the way the Sparton unit connected to the EZ-Wire harness for future reference.  These will be in the format of wire purpose, EZ-Wire color then Sparton color:

Brake Switch - White - Brown
LR Turn - Yellow - Blue
LF Turn - Lt. Blue - Yellow
RR Turn - Dk. Green - Orange
RF Turn - Dk Blue - Black
Flasher - Purple - White

From there I moved on to the ignition, starter and electric fuel pump relays.  The fuel pump gets three inputs to turn it on - a manual switch under the dash, the starter switch - so the engine gets fuel while cranking, and the ignition switch after being routed through an oil pressure safety switch (so if the engine dies the fuel pump stops running).

Note that if you go this route, you’ll need to use diodes on each of those fuel pump inputs - otherwise you’ll backfeed one from another and strange things will happen...trust me....

From here it was on to the engine compartment - which is pretty straightforward and hence no pictures…

Once all connections were made and tested with the 12v battery charger (or a multi-meter) it was time to try firing up the Jeep for the first time in a couple of years.  With the gas tank re-installed and some new gas it fired right up:

With the Jeep running again I took the time to tidy up the engine compartment and underdash wiring (the underdash pic shows both the auxiliary fuseblock that provides the switched power to the relays, and the somewhat hidden switches for the fuel pump, hazard lights and underhood light):

And also wrapped all the relay connections in rubberized electrical tape (not the typical vinyl gummy stuff):

By this point it was early November - so this project took me about 4 months to complete - but also with doing the wallhanging during that same time.  That’s longer than I expected, but I’m pretty happy with the results.  The dash looks great, everything works, and I know how it all goes together.

Just so long as I don’t lose all the pictures and notes I took along the way....