Joe Guilbeau

[Brown Bear]

I know you know your stuff when it comes to electrics.....you know much about automotive wiring? espeicially on an fsj? I'm wanting to make my own wiring harness and cut down all the crap that i can, since i'm going to be getting rid of all the power seats, windows, locks and such, and as much of the undherhood stuff as i can. You know what can go and what can stay? and how i should wire up stuff like headlights?

[Brown Bear]

Oh yeah....just read your other post regarding the poor guy's meltdown....i want to make my own voltmeter.....working on it now....how should i run the wiring to my new voltmeter, which will be made from an old multimeter? ;)

[Joe Guilbeau]

You can certainly make your own wiring harness for the Jeep.

One method is to get a plywood sheet 4-foot by 8-foot.

Now find a wiring harness out of another Jeep, or if yours if going to be "down" for some time, and mark the terminations of each and every wire with permanent black markers on Ty-Rap marker tags.

Now, remove the wiring harness (engine bay side) and lay it out on the plywood sheet.

If the harness has the wires bundled together, with tie raps and electrical tape, then that is a good thing. Route each of the bundles out in a fan pattern.

You will need a box of 500 4-inch finishing nails. What you are attempting to do is to put a nail every inch on both sides of each of the wire harness groups, to spread them out in a fan like position. Each group of wires will be routed in it's own corridor of nails.

See where this is going...?

Now that you have all of the groups of wires routed and laid out, take a look at then and visualize how they were routed in the engine bay.

Modify the nail corridors at this point to where you are satisfied, the original routing of the harness will retain the memory of it's routing if you are careful to remove it and not twist it around a bunch.

Now, you have to fan out the ends of the wire, using a staple gun or more nails to separate the ends and terminations. Ring terminals are easy, cause you can stretch out the wire and put a nail in it. Other terminations like spade lugs can use two very small finishing nails to "trap" the spade lug.

When you are satisfied with the whole shebang, you can now begin to remove all the ty-raps and electrical tape and plastic sheathing from the individual wire looms.

Once this is done, you can now examine the colors of the wires, and by adding up the lengths of the individual colors determine the number of feet of each color that is required.

You also have a good idea of the termination of the wires, the spade lugs, ring terminals, snap clips etc...

So it is off to an Electrical Supply house to get the wiring, terminals, and a good ratchet crimper, which should be Mil Spec, for about $45 dollars, with interchangable jaws for all of your termination needs.

Teflon insulated copper stranded wire is outstanding and slightly expensive, but if you are going to keep the Jeep, is well worth it.

Doesn't hurt to go one AWG size larger than stock.

Buy a new connector at for where the firewall is (I think that a late model CJ is the same) or find a NOS part, perhaps Painless Wiring will share their parts source vendor. I thing that a CJ plug will work.

As you remove each wire from the original plug, label and tag it with the Ty-Rap and permanent marker pen. Eventually, you will want to save this mock-up harness for later projects, like selling the next harness you make up to members of this board. Once you do one harness, it becomes pretty easy to do another.

Back to the harness, work with one wire at a time, routing it along the old harness, pretty soon your new harness will be laying on the old harness, now terminate all of the wires, and insure that the wires are plugged into the firewall connector properly.

Some things to keep in mind...using adhesive heat shrink on the new harness will make it look spiffy, put the heat shring on before terminating the wires.

When you terminate the wires, use a soldering iron after crimping the wires to flow solder into the crimp connection, try not to let the solder flow past the crimp section and back along the strands of copper. This will make the copper strands brittle and they will not flex as well, and will break off.

That is it in a nutshell. The essential wiring will be self evident, to the coil, the cruise control, the heater, wiper motor, headlights, alternator, etc...

You can remove the heavy gauge wire that comes from the Bat connection to the alternator, as this wire is routed thru the firewall on the plug. You will probably see heat damage on this wire or where it terminates to the plug. This wire takes the alternator charge voltage and current and runs it to the Amp gauge in the cab. Removing this link, saves Jeeps from fires.

Can buy a fusible link or circuit breaker matched to your alternators output, and run the alternator output directly to the solenoid.

Depending on the Alternator that you have, a wire from the battery to the No. 2 terminal on an SI alternator, and a wire routed from an Ignition "Run Position" switched 12Vdc thru an "idiot light" for charging...or as we fondly called them..."Visual Annunciators" will be routed to No. 1 terminal.

CS alternators Bat terminal connects the same as the above, and a wire from the solenoid terminal that is connected to the Positive Battery Post can be routed to the "L" terminal of the 4 prong connector. This is, of course, dependent on the specific regulator used in the particular alternator as there are at least 14 different variations.

That is pretty much it, go ahead and get after it, when you finish yours, you will know why Painless gets 400 bucks for theirs.

By the way, I would try to go to a local store that sold the painless wire harness, and take a long hard look at it.

I would run the voltmeter wiring directly from the battery to your in cab voltmeter, and use some heavy gauge (14 AWG minimum) wiring to do it.

Mount the gauge in the cab where you want it, and use one of the unused connection terminals on the firewall plug. Route the wire along the firewall past the heater, and along the fender well to the battery. After all, the Voltmeter that you are going to use does not draw any amps, so this will be fine.

For your headlights, I think that the most effective and sane method would be to purchase now headlights from an aftermarket supplier that has it own wiring harness and connections, and just lay it in the engine bay and wire it in.

This will take the better portion of a week to do.