2WD TO 4WD SWAP?

I just bought a 2wd 1993 4.0 HO with aw4 xj and will be converting it to 4wd with 1989 4x4 aw4 and 231 transfer case and front axle, my concern is are the different year transmissions controlled with diffrent electronics that I will need to swap or will it be plug and play , I know the 89 is a renix system and the 93 is chrysler electronics but dont know about the EATX controller if it will swap from one to the other? Any knowledge about this would be helpful before I start the swap.

It should be a plug and play. You can keep the existing Trans computer. It's located under the passenger kick panel, but you don't even need to touch it. You should be able to just unplug the two tranny connectors located on the passenger side of the firewall. One connector is the NSS sensor, the other is the solenoid and speed sensor wiring. Follow the two wiring bundles from the tranny to find them. I'm 90% sure the solenoid/speed-sensor wiring harness connector is identical between the 89 and 93. If it's not, can pull the pan and swap in your existing solenoid wiring harness. The NSS wiring connector should be the same, if not just use your existing one.

Electronically, the only thing that changed on the AW4 was in 1996 when the rear output shaft speed sensor changed type and the internal rotor that triggers it went from 1 pulse/rev to 4 pulses/rev. Even that would not be a big deal as I understand you can open the rear of the tranny and swap the rotors and use the existing speed sensor. The wiring harness connector changed in 96 as well.

Mechanically, at some point 4th gear in the AW4 changed from a 0.79 ratio to a 0.75 ratio. I "think" this was in 1991 when the output shaft spline count changed. The difference in 4th gear ratio won't affect the trans computer, but you might notice the 3-4 downshift happens at a 5% higher rpm.

As a reference point, I have a 1999 AW4 in my 89 Comanche. Aside from dealing with the rear speed sensor issue, it was a straight bolt-in. Since I didn't have an 89 tranny to get the correct rotor, I built an electronic box to convert the rear speed sensor output to what the 89 TCU was expecting. A 1989 NSS bolted right on.

I would recommend changing the front and rear seals on the 89 tranny and doing a fluid change. If you have the pan off, you can flush out the "filter" with some carb cleaner. Calling it a filter is a bit of a misnomer as it's really just a fine screen mesh.

lawsoncl covered it well. I was able to use my 94 2wd trans speedo assembly in the 88 aw4 i swapped into my conversion.

One thing not mentioned, the throttle kickdown cable for the trans will need to be swapped. A renix era cable will be too short in an HO application.

THANKS GUYS you have been a big help .!

ummm...why not just buy a 4wd XJ? they are cheap enough. esp the years you are talking about. i mean if you really wanna then do it, but i dont see the sense in putting time into such a project.

XJinCT said:

ummm...why not just buy a 4wd XJ? they are cheap enough. esp the years you are talking about. i mean if you really wanna then do it, but i dont see the sense in putting time into such a project.

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I dont see the sense in responding to someone's else's thread about their rational referencing how they spend their time and money. :moon:

John b , thanks for defending me and others, but I can do for myself. Here is my situtation, I bought a 1993 2wd 4.0 HO County model for 1000.00 with 120k miles on it I have unlimited access to a friend's wrecking yard where I can pull and sell anything I want on Ebay and split the profits 50/50 with him , we have a 89 4wd with 81k miles that was rolled. So for very little money I can swap everything over and be out not much more than my time. So the 89 will soon be missing a leather interior , trans, t/case front diff and anything else I need , motor is still available if anyone is interested.

My 92 XJ started Life as a 2wd, It is now a 4wd. Not to hard. If you look in the right places you can get the parts pretty cheap. Cost me about $1200, but I got completely built axles, trany, and t-case. I rebuilt the engine a year prior, so for about $3000 I got a new jeep with the goodies that I wanted.