88Comanche818

Your welcome. I normally wouldnt take that much time a make such a long post but I know exactly what positon you are in. I actaully bought my truck with a 4 1/2" lift on it, so it was really asking for a conversion. That and the fact that i was sick and tired of people complimenting my truck and then saying "oh.....WTF its not 4x4?". Now its my pride and joy. Good luck with yours. Randy B.

I went through this same conversion. I started off with a 88 Jeep MJ, Renix 4.0L, 2wd, Ba5/10. It makes things much easier if the donor is also a Renix 4.0. I found a 1989 Cherokee for $300 on craigslist which was rear ended. Frame was damaged but axles and all were OK. It ran well, and had 180K on the ODO. So now i had my project and a suitable donor. My engine was making a low knocking noise at some rpm's so i decided to do an engine swap as well while i was at it. It is best to keep the donor until your conversion is %100 complete. you never know what you might end up needing. Anyways it wasn't too bad. Me and a buddy did it in about 1 1/2 weeks. I have a very organized and well equipped work area/shop in my backyard (dads a mechanic) and 10 years experience working on cars. I am 23 years old. You will need to swap in the old auto ECU, auto TCU, Wiring harness which plugs in to ECU (including all sensor wiring/relay block), small trans harness which plugs into TCU behind passenger lower dash, comfort/power switch, throttle body, speedo cable, trans/tcase as a unit, donor d-shafts, shifter assembly / cables, etc, etc. Be patient and make sure you do it right the 1st time. There is alot involved. It becomes very difficult to diagnose any problem after a project this big. You have moved so much around that sometimes you may feel overwhelmed. It almost happened to me after my swap when i overlooked the ECU grounds. Make sure to clean them up and get them nice and snug, they go behind the oil dipstick on the bolt. When i was done che fired right up ad runs like a top. I used this "old" engine and trns and had great results. Engine runs much better then my old 4.0 which had around 300k, and has VERY good oil pressure. Trans was servced at time of conversion with new filter and fluid and it shifts perfectly. Trans fluid is still rosey red and smells as it should. Ive been driving it for 4 months now and have had no issues whatsoever. Only issue i had was related to the engine swap and not the 4wd conversion. I had a substantial leak from my oil pan and had to drop it to replace gasket and rear main seal. When i did i insopected the main crank bearing which i removed to replace rear main seal. i was soo surprised at the PERFECT condition that i found it to be in. I checked the back and it was standard size with the original AMC logo on it. Wow... what an engine, it really was hard to believe any bearigs could look that good after 180k miles. I put it all back together and now have gained peace of mind. I know my engine is good to go/has been well taken care of. After that my MJ hasnt leaked a drop, and runs like a champ. Your best bet is to find a suitable 87-90 Renix Cherokee/Comanche for your donor. Once you find one of these, you can be sure you have EVERYTHING needed to make your MJ 4wd. The only thing which i needed to have done was my rear drive-shaft. The MJ has a longer wheelbase than the cherokee, and thus the rear xj shaft won't be long enough. I ended up having my old long Mj shaft cut down and re-welded to the correct size. It works very well. Oh yah, the E-brakes also need to be modified to work somehow... its kinda tricky. I never got to that, as its no longer as important now that i have "Park" with my Auto. Find your donor, and let us know if you need anything else or have Q?'s.

Hahah PCM, meant ECU. You knew what i meant. lol :doh: I bolted up the ecu and gave it ground, and still the same thing. I have 2 wires running from my Alt plug... one yellow, and one tan w/ black line. What should be voltages or signals at these two wires?

So i just completed my 4wd conversions on my 88 MJ. Went from 2wd, ba10/5 to 4wd, AW4, NP231. I had to swap the engine compartment harness along with my ECU. So the jeep got running on the 1st crank, but my alternator is not charging. Gauge reads at 10v and i checked with DVM and its 11.90 at posts and same thing when i checked at alternator post. I had a spare alternator (known good), and i swapped it and still the same. I'm not sure where to look now. I'm gonna check for any open wiring again, but i did a pretty good look and found nothing. Any ideas? I know my power cable to alt has battery voltage so the problem is with the regulator. Another thing is i have not yet bolted in/grounded my ECU... its just sitting there in the cab. Perhaps it needs to be grounded as ive heard regulator is in the PCM... I need some helps ASAP, can't wait to test drive this thing.. Any tips anyone? TIA Randy B.

It would have been nice... but the donor is gone. To be honest i just can't afford to have it taking up room. I needed it gone so i could get the Manche in and start building it. Believe me though... i was quite thorough about it. I took everything and anything that could be possibly needed. The ONLY thing i MAY need and didnt keep is the body harness. I've been told engine/tranny harness will plug in, and I really didnt feel like tearing into the dash and unpluging / unrouting everything. Worst comes to worse, i'll be making a trip to the local pick-and-pull and tearing one out of another auto XJ. They are quite plentiful around here. Thanks again for all the advice/input! :clapping: :bowdown: Ill Update perhaps as i get some progress. Any Q?'s and ill be back. Thanks! Randy B.

OK, i assumed this was the body harness as it also goes in under the dash into the interior and has the 2 large plugs into the ECU. Ok, if that is it then its do-able. Awesome! Thanks a lot JeepcoMJ. :cheers: Ill go ahead and throw away my donor XJ now knowing that i got everything i need. Tomorrow hopefully the MJ goes on the operating table. =D Great info! Thanks again guys!

Of course i got the TCU. I still have the donor XJ, junking it tomorrow. Certain eh? Well i got pix to prove it now... Here are pix of my BODY HARNESS, with my TCU / transmission harness. All one piece... I either gonna have to splice... or most likely swap the whole harnes :mad: This is gonna suck... anyone gone through this? :help: :dunno: :???: [/img] if that doesnt work look here http://www.flickr.com/photos/28066721@N02/

Thanks! But that tranny swap page appears to be wrong... I wish the plugs were there and i could just plug in tranny plugs.

In my Mj it does not appear to be a seperate harness... I don't see the connectors to plug in the AW4 plugs. It appears to all be part of the body harness on the 88 XJ I'm using as a donor. Any help? Do i really need to swap the whole Harness? :doh:

I am currently preparing to convert my 1988 Jeep Comanche 4.0, 4 1/2" Lifted, Short bed, 5 speed ba-10, 3.08 gears, to 4x4. I just picked up a 1988 Jeep Cherokee as my donor vehicle. It has the 4.0 with AW4 and np231, dana 35/30 w/ CAD combo with 3.55 gears. My plans are to swap Engine/trans,X-case, and axles. Now let the questions begin.... I had not thought of the fact that the AW4 has some electrical components to it and i will apparently be needing to also take the harness to the TCU (Trans computer). I would hope / pray that everything is already in my MJ and just needs to plug in... but i doubt its that easy. So my question is... Do i need to use the WHOLE wiring harness from the XJ, or splice in the Trans wiring? Its quite a PITA to remove and disconnect everything under the dash, but if i must... Also, The comfort / Power switch... Do i need to wire all this in as well? Id like to just keep it in power mode by default like the newer AW4's, how can i do this? Also after removing the trans floor shifter i noticed 2 cables which move with the shifter. One was for the tranny shifting itself, and the other lead to my ignition column. I believe so that it locks / unlocks with the key on/off. Will my column in the MJ have the little linkage for the cable to hook up? or do i need to swap column as well? I was thinking it may not be necessary and i could possible leave it out and have no negative effects... but i'm not sure. One more question... What if anything my i be forgetting to remove from donor XJ? Ive pretty much completely stripped it already and am ready to call the junk to come take it. I'm only worried that there is surely gonna be SOMETHING that i forgot to remove and will eventually have to pay for another one. Hoping i've covered everything, but for those who have done this conversion, id like to ask. What are the overlooked things that i may need? Also Planning on welding the D30 and setting up a hombrew POSI-LOK setup. Any recommendations / suggestions? Good or Bad idea? Sorry for the long post, i like to be thorough. Any feedback is much appreciated. Negative or Positive, Let me know. ALSO... If you need random interior / body parts come and take em... Take whatever you want for little or nothing... I'm locating in the San Fernando Valley, 818, 20 mins north of downtown LA. Thanks in advance... Randy B.