Wiring harness compatibility

[Geeknahalf]

Hi folks,
Will an engine wiring harness from an 03 tj rubicon 4.0 w auto trans, work in its 04 non rubicon counterpart?

Thx in advance!

 

[hear]

Short of somebody just telling you the answer (assuming somebody knows the answer), I would compare section 8W in the FSM for both years, and specificlly look to see if there are any notations that indicate that something was different on the rubi.

I bet it will be pretty close though. And I would guess that it's more likely that a rubi would work in a non-rubi thn the other way 'round. But the wiring diagrams are going to be your best resource. Those can be found in our Resource section here.

 

[JMT]

I don’t have experience with that particular swap, but that one should be a straight swap. They were both pre-NGC. I can’t think where they would differ. The break was ‘03-04 and ‘05-06.

 

[mrblaine]

Hi folks,
Will an engine wiring harness from an 03 tj rubicon 4.0 w auto trans, work in its 04 non rubicon counterpart?

Thx in advance!

Yes, but don't toss or get rid of the old harness until the swap is done. It is likely that you will need to move an O2 connector around to get it to work.

 

[lowell66dart]

Take the part numbers off of both underhood fuse boxes. Go to the nearest dealer and ask the parts guy if they are compatable. I did this when I was doing my Hemi swap. I sourced another harness to send to Hotwire as I did not want my Jeep sitting for 3 months. The numbers change for various reasons such as one may have the connections for cruise control, one may not.

 

[Geeknahalf]

Hi Folks,

Thanks for the responses!

I tried looking at the FSM. However, try as I might, I simply cant make heads or tails of those diagrams. From the google searches I did, it seems the harnesses are compatible. Gonna take a chance, hopefully it will be here early this week. I'll update the thread with the results. Here's to hoping this fixes my issues.

The harness cover with the part number was lost a long time ago, that's a good idea with the fuse boxes to check compatibility.

I'm holding onto the original(?) harness until I know the replacement works/works better.

I believe there is an issue where the harness crosses over the valve cover. When idling, I moderately twisted that spot and the vehicle shut off. I have remove the harness and all of its looming, exposed all the wires, inspected them individually and can't find anything wrong. I'm currently using multimeter to check continuity of each wire. Hopefully that will produce something. The harness was previously spliced before I bought it, so who knows what's what.

Also-- a short while ago I had the hazards, windshield wipers, and dash components go crazy on me while I was driving. I wasn't able to turn them off, however, they stopped by themselves shortly there after. I found I had forgotten to tighten the grounds located next to the headlights when I reinstalled the front grill area. Since tightening them, I haven't had any further issues like that. Would something like that damage the ECU?

It's been two years and thousands of dollars I've invested (been fighting) with this thing to get it running right. When it runs right, it puts a smile on my face. Unfortunately, each time I fix one thing another issue crops up. It's my first jeep and I really don't want to get rid of it. That said, I'm getting tired of putting money into it and working on it every weekend. I work on it more than I get to enjoy driving it.

Again, much appreciate the responses!

 

[mrblaine]

Hi Folks,

Thanks for the responses!

I tried looking at the FSM. However, try as I might, I simply cant make heads or tails of those diagrams. From the google searches I did, it seems the harnesses are compatible. Gonna take a chance, hopefully it will be here early this week. I'll update the thread with the results. Here's to hoping this fixes my issues.

The harness cover with the part number was lost a long time ago, that's a good idea with the fuse boxes to check compatibility.

I'm holding onto the original(?) harness until I know the replacement works/works better.

I believe there is an issue where the harness crosses over the valve cover. When idling, I moderately twisted that spot and the vehicle shut off. I have remove the harness and all of its looming, exposed all the wires, inspected them individually and can't find anything wrong. I'm currently using multimeter to check continuity of each wire. Hopefully that will produce something. The harness was previously spliced before I bought it, so who knows what's what.

Also-- a short while ago I had the hazards, windshield wipers, and dash components go crazy on me while I was driving. I wasn't able to turn them off, however, they stopped by themselves shortly there after. I found I had forgotten to tighten the grounds located next to the headlights when I reinstalled the front grill area. Since tightening them, I haven't had any further issues like that. Would something like that damage the ECU?

It's been two years and thousands of dollars I've invested (been fighting) with this thing to get it running right. When it runs right, it puts a smile on my face. Unfortunately, each time I fix one thing another issue crops up. It's my first jeep and I really don't want to get rid of it. That said, I'm getting tired of putting money into it and working on it every weekend. I work on it more than I get to enjoy driving it.

Again, much appreciate the responses!

If the harnesses are both 03-04, they are interchangeable except for 1 or 2 O2 sensor connectors.

They are showing more to be 04 only but we only had to change one connector by depinning it and swapping it over.

 

[Geeknahalf]

Excellent, thank you Mr Blaine. Also the brake pads I bought from you work amazing!

Wish me luck folks!

 

[Geeknahalf]

Quick update, based on the map sensor connector’s match at O’Riellys \ checkers, the harness is from 02.

I’ve researched the internet with very limited results.

Anyone know if this will work?

Thanks again!

 

[mrblaine]

Quick update, based on the map sensor connector’s match at O’Riellys \ checkers, the harness is from 02.

I’ve researched the internet with very limited results.

Anyone know if this will work?

Thanks again!

Compare the fuse and relay locations and requirements. I believe that you will need the ATX circuit for the 03 and it is missing in the 02.

 

[Geeknahalf]

Hi Folks,

Sorry for the way too late update.

The swap didn't work. Harness was an 02 not an 03, split year, and a Canada model or the like that had only 2 O2 sensors. Was everything it shouldn't have been, and I wasn't able to get it to work. Def not what the seller listed.

Wound up removing the factory one completely, stripping all the looming off and continuity testing every single wire, replacing the broken connectors to the sensors\modules, and rewrapping the entire harness.

Joy.

Its up and running but, still not sure if its working right. I have the firewall ground to the eng. disconnected. If I connect it, all 4 O2 sensors come up with heating circuit low voltage and the engine runs like crap and shuts off. Then it wont start until i clear adaptive learning.

I swear I have gremlins.