Simply, where to purchase a new wiring harness? 94' YJ


DrivingDuncan

New Member
Joined
Mar 15, 2021
Messages
1
Location
College Station, Texas
Good evening all,

I am helping my dad out by getting his jeep up and running again. This Jeep YJ being 26 years old, he wants some replacement parts. One of those are a new wiring harness. This jeep is a 4.0 straight six manual.

O'reillys is attempting to find one for me with no answer yet.
I cannot find any brand new harnesses online, that will come pre-made. Perhaps I'll have to reassemble a new one?

I am wondering which direction to look, if there is some hidden gem for premade wire harnesses that I don't know about. Or is it even worth it?

Any help is greatly appreciated!
 

machoheadgames

Certified YJ Researcher
Supporting Member
Joined
May 19, 2020
Messages
320
Location
Dallas, TX
Good evening all,

I am helping my dad out by getting his jeep up and running again. This Jeep YJ being 26 years old, he wants some replacement parts. One of those are a new wiring harness. This jeep is a 4.0 straight six manual.

O'reillys is attempting to find one for me with no answer yet.
I cannot find any brand new harnesses online, that will come pre-made. Perhaps I'll have to reassemble a new one?

I am wondering which direction to look, if there is some hidden gem for premade wire harnesses that I don't know about. Or is it even worth it?

Any help is greatly appreciated!
There are no new ones. Buy from eBay or fix up the old one. Are there specific issues with the existing wiring that warrant a replacement?

The YJ is broken up into multiple harnesses that connect together:

Headlight Harness: includes horn, washer motors, and all front lighting - headlights, parking lamps, fog lights (if equipped), side markers). This one starts at the bulkhead fuse box connection on the firewall and runs down the driver fender and then over through the grille. The headlight harness will usually only include wiring for fog lights if the YJ was equipped. Same goes for the dash harness with the fog light switch connector, it is usually missing the connector if the vehicle had no fogs ever. Sometimes this is not the case, and a Jeep without fog lights may still have all the wiring. It is a messy mix. Mine had no fogs and no wiring or switch connector for them.

Engine harness: Goes to injectors, sensors, sending units, etc. Starts at the PCM, goes up to the firewall and to the engine, down the engine and back around, then down the passenger side of the engine at the firewall and out to the transmission, transfer case, and fuel tank. It connects to the body harness at 2 connection points, 2 cube connectors, one located at the relay box by the alternator and another one at the firewall. These connections are how the PCM gets power and how the sending unit data gets back to the gauges.

Under hood Body Harness: This one includes the relay box, and is really how power gets from the battery to all the vehicle components. The relay box has a bunch of wiring coming out of it, some goes to the engine harness through the connectors previously mentioned, but most of it goes up to the top of the firewall and over to the bulkhead connector (the same one the headlight harness goes into. The headlight harness actually clips into the bulkhead connector on the under hood body harness.

Often eBay will sell the engine harness & under hood body harness together and just call it "engine harness".

Under dash body harness: This one feeds all dash components (speakers, gauges, radio, heater, courtesy lamps, etc). It runs from the fuse box and carries power across the dash. It has two boxy connectors (gray and black) by the fuse box that connect to the rear body harness.

Rear body harness: This one feeds tail lights, seat belt buckle sense, and the appropriate lack of wiring for a soft top, or wiring/hose for a hard top, hard top defroster (if equipped), hardtop window sprayer, and the hardtop dome light. There were multiple harnesses for all these options, they built the harness depending on what features you have. Meaning my harness has everything but hardtop defroster wiring since my hardtop didn't have a defroster.

Hope all that helps. Nobody makes a full YJ harness. Painless makes a harness for the body of an 87-90 carbureted YJ. It is not painless, as there are a lot of items that have to be kept and reused if still running one of those engines. For a fuel injected YJ 91+, you can still find all 5 of the harness types on eBay, in their different variations as well. Just search. They're all old so unless you're having problems, I'd keep what is there.
 
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jeepjoe43

YJ Enthusiast
Joined
Dec 4, 2020
Messages
242
Location
Black Canyon City, AZ 85324
It's Major Pain in the Butt to remove and rebuild a harness, but at least you will KNOW what you have.
With a used harness you're probably buying problems from someone else.

This is my 10 step program to go about rebuilding one.
1 Label All of the connectors and carefully remove the harness from the vehicle.
2 Spread the harness out on piece of plywood securing all the connector with screws and zip ties.
3 Use screws or nails to mark everywhere the harness branches so you get them back in the right place later.
4 Inspect all the connectors for corrosion or other damage. (Probably where you'll find your issue if it's the harness)
5 Remove all of split loom and label the size of the loom on the plywood.
6 Inspect for physical damage to the wires. Wiring faults tend to be obvious, but are usually at a connector or a splice.
7 Use a meter to check the continuity of each circuit, wiggling each connection as you go.
8 Repair or replace any faults found, most of the connectors can be disassembled with the right tools if needed.
You won't be able to "uncrimp" an original connector, but you can solder a new wire to it.
9 Replace the split loom with New and Gaffers tape or branch connectors where needed.
10 Reinstall.

You will likely have found and fixed the problem, and it'll be pretty again.
As a laddy my father taught me that if you're going to take something apart to fix it, clean it, fix it, paint it if needed and make it New.
Doesn't work in every situation, but that's my Modus Operondi.