Help with 4.0 swap - Page 4 -
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post #46 of 51 Old 09-20-2012, 08:37 PM
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1994 YJ Wrangler 
Join Date: Apr 2011
Location: Orange Park
Posts: 1,941
Originally Posted by Que89YJ
Yes the ecu will work and he has multiple harnesses. Both of you get in touch with him and tell him I sent you.
Well then I should be in like flynn once i get the harness in the mail... as long as there are no other issues. Crossing my fingers.... oh I have 2 harnesses for sale too ... and a whole bunch of other stuff clogging my shed

Wave as you pass me :D

The problems of owning 2 Jeeps ... I never know which one to work on or which YJ gets the next mod ...
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post #47 of 51 Old 11-05-2012, 10:08 AM
Web Wheeler
1989 YJ Wrangler 
Join Date: Apr 2008
Location: Detroit
Posts: 24,676
I have been out of the loop trying to get my car running again. Did you get it figured out?
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post #48 of 51 Old 11-05-2012, 11:48 AM
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1988 YJ Wrangler 
Join Date: Jul 2012
Location: Huachuca City
Posts: 364
Hey guys, I know this thread is a few weeks old, but depending on where you are at in your harness struggles, I got a complete harness (for the whole jeep) on ebay for $250. I had to do that as my yj is an 88. Since you both have 91 or newer YJ's, you should be able to just use the 4.0 engine harness. If I remember correctly, it is a plug and play to the 2.5 bulkhead connector, but you want to check it just to be sure. I got my harness at

This should make you wiring a whole lot easier and you wont have a rat's nest.

By the way, the reason that I had to get the whole harness is because I went from a carbed 4.2 to the 4.0. I had to redo my gauges to the newer style, basically the entire jeep. You guys are ahead of the game because you have the newer jeeps. Hope this helps.
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post #49 of 51 Old 11-05-2012, 12:00 PM
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1988 YJ Wrangler 
Join Date: Jul 2012
Location: Huachuca City
Posts: 364
Update: I just checked and he doesn't currently have a 4.0 engine harness listed, but check back in a couple of days and he should have one. You can also call them and see when he will have one. It made life so much easier for me when I did mine. I started by doing the "5 to Fire" process I found on line and ended up with a worse rats nest than you guys have.
Again, hope this helps.
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post #50 of 51 Old 11-05-2012, 02:08 PM
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1992 YJ Wrangler 
Join Date: Nov 2010
Location: Hazel Park
Posts: 298
Also curious if things worked out for Mrmark. My jeep is currently running sans speedo, but would love to just put in a stock 4.0 harness if it's really that simple.

From 2.5/AX5, 30" Geolander, 2" BL
TO 4.0/AW4, 2.5 OME SOA, 5/8" boomerangs, 8.8 Aussie locked, D30 CAD eliminated, 35" Radial Rover, JCR 4x4 front and rear bumpers, ENGO 9000, Volvo e-fan, TJ rock rails, etc etc.
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post #51 of 51 Old 11-05-2012, 03:38 PM
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Join Date: Mar 2010
Location: Vernal
Posts: 2,791
I have been out of the loop as well. I like hearing success stories on these 4.0L swaps as that mine was a success as well.

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