Novak Conversions Jeep Wrangler YJ radiators

Rewiring Engine Harness - Connector Identification Help Needed

94-92 YJ DFW

94-92 YJ DFW

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Joined
Apr 29, 2024
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Location
Dallas
I am a pretty new Jeep owner here looking for some assistance with wiring connectors. I bought a 94 Wrangler with a 4.0L with an AX15 manual transmission, no AC, after I did some digging I found that the vehicle originally had the 4 cylinder engine so at some point a previous owner swapped the motor in a typical bubba fashioned install. The first issue I tackled was the motor would not stop running when I turned the key off. I realized that they had bypassed relays and wired constant voltage to the computer not allowing the PCM to recognize when the key was turned off. After more digging, I found main harness connectors cut, it was a real mess. I also noticed they installed an external voltage regulator which I assume must have been due to either a PCM voltage regulator internally failed or just a hack job of an installation. I replaced every capacitor in the PCM with a good solder job. After trying to fix the harness I decided to buy an uncut original harness from Dead Jeep since the job was pretty massive to fix the old one.

So I am at the point of connecting everything up, I have pretty much every main connector hooked up such as the MAP, TPS, crank position, cam position, coolant temp sensor & temp to gauge, o2, oil pressure, intake air sensor, idle air controller, distributor, coil. I am left with only a few connectors that are not connected, and want to ensure I have them correct.

I think two might be for if I had AC installed, the AC high pressure switch and a single blue/black larger gauge wire that might go to the AC compressor. Pictures below:
IMG_2535.jpeg
IMG_2558.jpeg


And then I have one other connector that splits off the loom going into the PDC. There is a connector it fits to right under the PDC that seems to head toward the transmission, although I think I have the neutral/park switch connected and the speed sensor connected already. Shown in pics below the second pictures wires are one black and another light blue or light green with a white stripe:
IMG_2552.jpeg
IMG_2519.jpeg


Below are all the connectors with a wider shot:
IMG_2548.jpeg


I certainly appreciate any assistance anyone can provide. I am hoping to get this rig up and running for my daughter as this is her first Jeep ever, she is excited to be a YJ owner! I apologize if this is a repeat ask, I figured with my wiring situation it might not be but who knows.
 
How did you determine it was originally a 2.5L and was swapped to 4.0?

The first connector is definitely the single connector for what would be a missing AC compressor.

The second connector is not common but it does look like it's for some type of AC drier. The normal connector for the AC drier looks different, and so what I've seen on most all other YJs does not match yours. But based on location, that is probably what it's for, the hi/lo pressure switch.

The 3rd and 4th connectors I believe plug into each other to power the 4x4 light when the front differential actuator shifts. Can you plug them into each other?
 
machoheadgames said:
How did you determine it was originally a 2.5L and was swapped to 4.0?

The first connector is definitely the single connector for what would be a missing AC compressor.

The second connector is not common but it does look like it's for some type of AC drier. The normal connector for the AC drier looks different, and so what I've seen on most all other YJs does not match yours. But based on location, that is probably what it's for, the hi/lo pressure switch.

The 3rd and 4th connectors I believe plug into each other to power the 4x4 light when the front differential actuator shifts. Can you plug them into each other?
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Thank you so much for your help. I checked the VIN and it showed it was a total swap. I assume the transmission might have been as well as from my understanding the AX-15 wasn't supplied with the 4cyl. I think you might have nailed it on the first two, I am thinking its for AC components as well. The 3rd and 4th, I am still unsure. The 4th where you can clearly see the PDC, that one plugs into a matching connector right below the PDC, when I get home I will trace where that connector leads to.
 
94-92 YJ DFW said:
Thank you so much for your help. I checked the VIN and it showed it was a total swap. I assume the transmission might have been as well as from my understanding the AX-15 wasn't supplied with the 4cyl. I think you might have nailed it on the first two, I am thinking its for AC components as well. The 3rd and 4th, I am still unsure. The 4th where you can clearly see the PDC, that one plugs into a matching connector right below the PDC, when I get home I will trace where that connector leads to.
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Okay, the 4th is definitely for the 4WD, I know that for sure because of how it comes out of the PDC loom. If you found the connector it plugs into down below, then the 4wd part is settled. that just leaves the one other connector that I am not sure about.

I see now how you mentioned about the 4th connector plugging in down below, and that running out to the transmission. In stock form, that would not be correct, what it would plug into would be the vacuum harness bundle and the wiring portion would go up to the front axle.

It would help if you can get a photo of the top of the transfer case and if you could also take a photo of the front axle actuator area. Curious if they did a 1 piece axle conversion or something and moved the 4wd light switch over to the transfer case.
 
I remember now that this one is the one where the engine was mounted too far forward and that it was a swap. I was thinking you were new to the forum and not the same one that posted about that before. Makes more sense now.
 
I am that guy, haha. I have been dealing with a ton of issues on this thing. I didn't want to give up on it, but had other things pop up that took precedence for awhile. For now I am leaving the motor where its mounted, I found a decent electric puller slim fan design that will fit between the motor and the front of the engine, the mechanical fan wont fit. Hopefully that will fix that issue. Then I had all the wiring issues to tackle, which should be resolved now with the new wiring harness.

I also need to address the rear drive shaft, the boot was missing and the spline shaft is seized, so I will most likely get a replacement shaft from here: https://www.dennysdriveshaft.com/p4...driveshaft_2_inch_tube_diameter_spline_a.html unless someone has one I could buy.

Its been fun, learning all about YJ Jeeps, I am a Bronco guy, so its a bit of a change for me.
 
machoheadgames said:
Okay, the 4th is definitely for the 4WD, I know that for sure because of how it comes out of the PDC loom. If you found the connector it plugs into down below, then the 4wd part is settled. that just leaves the one other connector that I am not sure about.

I see now how you mentioned about the 4th connector plugging in down below, and that running out to the transmission. In stock form, that would not be correct, what it would plug into would be the vacuum harness bundle and the wiring portion would go up to the front axle.

It would help if you can get a photo of the top of the transfer case and if you could also take a photo of the front axle actuator area. Curious if they did a 1 piece axle conversion or something and moved the 4wd light switch over to the transfer case.
Click to expand...

I'll take some pictures for sure. There is the eject button installed (lol I know people always ask about the red knob in the interior) that deletes the vacuum operated 4wheel. I am unsure if they put the kit in that allows the light to still operate without the vacuum system/switch installed.

I noticed you are in the N TX area, are you part of Jeep clubs in the area? I'd like to join one for sure.
 
94-92 YJ DFW said:
I am that guy, haha. I have been dealing with a ton of issues on this thing. I didn't want to give up on it, but had other things pop up that took precedence for awhile. For now I am leaving the motor where its mounted, I found a decent electric puller slim fan design that will fit between the motor and the front of the engine, the mechanical fan wont fit. Hopefully that will fix that issue. Then I had all the wiring issues to tackle, which should be resolved now with the new wiring harness.

I also need to address the rear drive shaft, the boot was missing and the spline shaft is seized, so I will most likely get a replacement shaft from here: https://www.dennysdriveshaft.com/p4...driveshaft_2_inch_tube_diameter_spline_a.html unless someone has one I could buy.

Its been fun, learning all about YJ Jeeps, I am a Bronco guy, so its a bit of a change for me.
Click to expand...

Makes sense, hopefully the fan option solves the placement issue.

For the driveshaft, I'm curious about the boot. Is it a stock style driveshaft or a double cardan aftermarket shaft? The stock YJ shaft doesn't have a boot, because it is sealed at the slip yoke. The TJ version of the transfer case sealed the transfer case at the rear output bearing and then the tailshaft stuckout and the driveshaft went on it and had a boot clamped to the driveshaft and to a shoulder on the tailshaft I believe, or maybe it was a dust shield. Regardless, no boot in stock YJ form, so that raises a red flag or two.

Denny's should be a good place to get a driveshaft if you need one, although they refused to build me a stock style driveshaft, which was a bummer.

94-92 YJ DFW said:
I'll take some pictures for sure. There is the eject button installed (lol I know people always ask about the red knob in the interior) that deletes the vacuum operated 4wheel. I am unsure if they put the kit in that allows the light to still operate without the vacuum system/switch installed.

I noticed you are in the N TX area, are you part of Jeep clubs in the area? I'd like to join one for sure.
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If you have the knob, then yeah you probably have the cable operated version. Technically that kit tells you to cut off your 4WD plug and rewire the wires to the cable operated housing, so that the light still comes on when you pull the knob. However, since you know you are working the cable, some people probably prefer to move the 4WD light turn on over to the transfer case so that it is specifically telling you about transfer case status and not front axle status. The factory runs the status off of the front axle because the front axle can't do anything until the t-case is shifted, so it's a bit all inclusive there and so they put the light to work off of the final component that operates.

I am in NTX, up in Plano. I am not in any clubs. Doesn't mean I won't join one someday, but I feel the vast majority of people in the clubs are not the type I typically would spend time with (non mechanical, don't really know anything about what they're driving) and so I haven't bothered to join one. But part of that also is that mine went under the knife in 2020, and I am just now finally getting it to a point where it is drivable, so there was 0 reason to join a club to begin with for a while because I haven't been able to drive it. I've only lived up here since 2019, so really there just hasn't been time. I may look for some sort of club with some technically minded members to hang out with, but I don't know. Still working on dialing in the driving characteristics of mine before I do anything with it.
 
I am not familiar with what a stock YJ drive shaft looks like, I just assumed that it was stock. I need to stop assuming on this Jeep, seems like nothing is stock or normal on it.

Below is a picture of the drive shaft.

driveshaft.jpg


Regarding the cable for the 4 wheel drive, the red cover dry rotted and a little shaft popped out somewhere. Sounds like I have to look at what to do there as well, I am going to do some research.

That's good to know about the clubs, I sound pretty green when it comes to YJ's just due to not knowing what to look for or how they came stock but I do have decent experience with older trucks and cars, mostly carbureted OHV V8s, Fords. My main rig is the 71' Bronco that I would like to get back to when this thing is running. I am hoping to find a group that is more technical as well, not just throwing ducks in the tub and joy ride around haha, not that there is anything wrong with that. Again I appreciate the assistance, you have been a huge help, my wiring diagram did not match the wire colors so those last couple connectors had me scratching my head. I am about 30 min from your area, always happy to help if you ever need it.
 
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94-92 YJ DFW said:
I am not familiar with what a stock YJ drive shaft looks like, I just assumed that it was stock. I need to stop assuming on this Jeep, seems like nothing is stock or normal on it.

Below is a picture of the drive shaft.

View attachment 123953

Regarding the cable for the 4 wheel drive, the red cover dry rotted and a little shaft popped out somewhere. Sounds like I have to look at what to do there as well, I am going to do some research.

That's good to know about the clubs, I sound pretty green when it comes to YJ's just due to not knowing what to look for or how they came stock but I do have decent experience with older trucks and cars, mostly carbureted OHV V8s, Fords. My main rig is the 71' Bronco that I would like to get back to when this thing is running. I am hoping to find a group that is more technical as well, not just throwing ducks in the tub and joy ride around haha, not that there is anything wrong with that. Again I appreciate the assistance, you have been a huge help, my wiring diagram did not match the wire colors so those last couple connectors had me scratching my head. I am about 30 min from your area, always happy to help if you ever need it.
Click to expand...

I missed this post because when I first saw it, there was only the pic of the driveshaft and I forgot to come back and check for text later.

That driveshaft is aftermarket, and is a double cardan style. Some also refer to it as a CV driveshaft (constant velocity), though it isn't really. It's just a driveshaft with a double cardan joint. To use that driveshaft, that means a previous owner converted the transfer case to having a fixed output yoke, meaning they installed a slip yoke eliminator kit. The factory driveshaft has a slip yoke that slides in and out of the transfer case tailhousing as the suspension cycles. The stock driveshaft connecting to that slip yoke and the rear axle is a standard 2-joint shaft. I'll provide a photo of mine below for reference.

IMG_1217.JPEG

As you can see, your transfer case comparatively will now have a fixed yoke on it, and the driveshaft has a slip built into itself instead.

Ah, since the cable is falling apart, who knows if it works then. Maybe it can be fixed, or might just want to replace it. Personally I like the vacuum setup better than the cable, because it's simple and works. But it has it's flaws too, mostly with lift the hoses get stretched out and break or pull off of the barbs they go to, rendering the system not functional.

For the clubs, I get it. Most of the people in the clubs are not technical about any vehicle. I like to learn about them all, so I'm always working on any truck I own, or my YJ. You ask a question in the local clubs (North Texas Jeep Club is the biggest offender) and they'll just tell you to take it to one of the two popular shops in the club. And yes, so many duck activities....lol. Anyways, I am still curious about that one unknown connector. That is a weird one. I'll keep you in mind if I need a hand. I can also help out if there's something you're struggling with. If you need some comparative photos of my under hood harness, let me know.
 
Well, I got it started and running to discover cav9, G50 start and run wire sends no voltage from the PCM to the ASD and Fuel pump relays. I jumped cav5 from the data link port which is G50 wire and the relays all click and get voltage. There is supposed to be 12v from ignition switch A21, there is a fuse then to wire G50 to cavity D5 on the bulk head connector to G50 which goes to relays and cavity 9 on PCM. I cannot find the metal prong in D5 on the connector. Can anyone send a picture of theirs to compare? I am trying to trace if A21 from ignition switch sends power to G50, through bulk head connector to PCM at cavity9, wire G50.

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Based on that diagram, it does seem like you should definitely have a pin at the D5 spot on the fuse block. Based on the bubba hackery you've seen before, I wouldn't be surprised at all if they removed it at some point. I'll pop my bulkhead off when I'm home and take a look at mine. I also have one or two dash harnesses in the house, I'll check them out too.
 
So I looked at mine for a bit and comparing with the diagram made me realize the diagram is for the hood side connector, which then you have to mirror to figure out the correct spot on the bulkhead fuse box connection.

It appears you do have D5 populated if my eyes aren’t playing tricks on me. As do I.

Yours:

IMG_1464.jpeg

Mine:

IMG_1462.jpegIMG_1455.jpeg
 
Well, I can report back and say that its now running, turns off and on with the key, check engine light comes on as well briefly as it should. The ignition switch I bought new out of the box is bad. I put the old one in after surely fixing the wiring issues with the old harness (the old ignition switch would not turn off the engine) and all is good. Holy crap, my advice, buy the $300 wiring harness from a reputable place like DeadJeep and save your self the time if you have a mess of a harness like I dealt with. Its worth the time alone. Hopefully this thread helps someone.
 
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