Auto Transmission Swap Compatibility

[Digger87xj]

You will get your answers at the connector for the fuel pump when you test for power and ground.

jump the relay and put your ear to the open filler neck

if you don't hear the pump get underneath and disconnect the fuel pump harness, test for 12v on the darkgreen/white wire
test for ground on the black wire. This ground leads to a terminal ring behind the left rear compartment trim.

if all test good, i.e. you have power and ground, time for a fuel pump module.

 

[QuillsXJ]

Just a quick update, I had only a few minutes last night and without a voltmeter I was able to test the following:

-Had friend turn ignition on and I had my hand on the fuel pump relay. I felt it click and heard it.
-I pulled the relay and tried a jumper wire between pins 87 and 30 (with ignition off) and then walked to back of jeep to listen for pump and I heard nothing.
-I ran a long piece of home audio speaker wire direct from positive battery terminal all the way to the orange/red power terminal on the disconnected fuel pump connector and heard nothing.
-I took off my battery clamps and re-cut and wire-brushed the wires/terminals and bolted the clamps back together and put them back on the battery.
-I still couldn't get a check engine light to come on by unplugging three injector connectors all at once and then cranking.

I am going to be out of town for a training the next few days, but so far all signs point towards the fuel pump being shot. This weekend I will volt test the fuel pump wires, check fuel pump ground and then replace the pump.

Thank you!

 

[QuillsXJ]

Before I left town I tried one last thing for the heck of it; starting fluid! The engine came to life like a raped ape! The engine would die out whenever I stopped spraying it in the throttle body. New fuel pump this weekend!

 

[kastein]

Awesome, here's hoping the tranny works great and the PO tried to conceal the engine or ECU "being dead" by pulling the battery, all over a fuel pump...

 

[QuillsXJ]

Over the weekend I swapped out the fuel pump and now the engine runs great considering it hasn't been ran in 3+ years. That was a relief… but my issues are not over yet. I went to put the Jeep in “Drive” and there was unfortunately “no go”. I tried all gears and the engine would just rev up and no movement. After trying this for a few minutes on level ground the Jeep started ever so slightly creeping forward very slowly in drive with the gas barely applied and the same thing in reverse. Essentially my buddy and I got the Jeep to move about 10 feet forward and 10 feet backward. It was really weird. I don’t know what to do or check as there is no CEL on. I tried unplugging the connector under the dash for the TCU and driving but no difference. I also pulled the bellhouse viewing cover and I noticed no real signs of metal or anything, only ever so slight amounts of trans fluid at the bottom of the housing. The torque converter seemed to be mounted firmly to the flywheel. Also, the transmission seemed to select and shift gears just fine. Any recommendations on what the problem could be or what to check would be appreciated.

Thanks again!

 

[bluejeepkid]

90 and earlier won't work without a significant rebuild and parts swapping.
91-97 won't work without a fairly significant rebuild and parts swapping, less than 90- but not easy.
98-01 are bolt in.

More detailed info: http://www.naxja.org/forum/showthread.php?t=1053970

Make sure you get one that's the proper 2wd vs 4wd version. Converting back and forth from 2wd to 4wd is as difficult as converting from a 90 and earlier to fit a 98 and later, not for newbies, unless you really want to do a rebuild that is more complex than simply rebuilding your existing transmission.

You can make a 91-97 trans (slight wiring differences across those years, but nothing complex) work with a 98 and later if you pull a 97 (only 97, make sure the part number is 5602 7951) TCU and install it and do some wire splicing.

I swapped in a 91 Aw4 into my 97. I had to swap the entire trans wire harness and solenoid wiring from the 97 trans into the 91. Not difficult, even for my first time dipping my fingers Inside a tranny (;. I luckily got to do it with both trans on a bench. I wouldmt want to do it if one was in the vehicle still.

 

[kastein]

You don't have to swap the whole harness, you can just cut and splice the wires to the solenoid that go into the housing, but I can understand why you'd want to do it right instead of cutting and splicing.

It sounds like that trans may be smoked after all, check level if you haven't already but it's not sounding good. Dumb question, you had the transfer case in gear, right? A friend and I got as far as pulling a transmission back out and putting it back in a few years ago before realizing we had left the transfer case in neutral. :doh:

 

[QuillsXJ]

Hey Kastein, the Jeep is a 2wd. Tonight I am pulling the pan to check for fluid quality, refill to the correct level, and to swap the filter and pan gasket. I was thinking about even running a bottle of SeaFoam Trans Tune to try to free up any sticky parts or solenoids too. I agree, I think there is only a 5% chance this will work, but worth a try before I get too far into it with another trans.

I have been corresponding with a seller on Craigslist of a 1997 AW4 that he just pulled from a 2wd in working order. In one of your earlier posts you claim that this swap is a headache. At only $200 it may be my closest shot at a replacement in my area. I am determined to get this Jeep back on the road! lol

 

[kastein]

:doh:

I completely forgot you said it was a 2wd.

A 97 will work, if you swap the TCU from the 97 as well... make sure it is a 97 TCU. Or if you do a ton of work that is really a headache.

Your other option (which I think I may have mentioned, but not sure) is to swap in an NP231, 4x4 rear driveshaft, and 4x4 98-01 trans, which leaves you way closer to a completed 4x4 swap. And 4x4 AW4s are everywhere. You could do a 4x4 97-down trans as well, same thing about swapping the TCU from a 97 will fix that too.

 

[QuillsXJ]

Thanks for your help Kastein! To clarify, if I get the '97 TCU and 2wd trans only is there any wire splicing or part swapping that I need to do or is it just a straight bolt-in procedure?

 

[kastein]

Well, there's two ways to go.

1. wire splicing - splice the wires that go into the trans itself, splice the connector for the OSS. Ignore the ISS.
2. pull the pan off both trannies, swap the complete harness from the old tranny to the new one, swap the tail cone/extension housing and OSS + magnetic rotor from the old one to the new one. You will want a good set of lockring pliers.

Personally I lean towards splicing the wiring.

 

[QuillsXJ]

I got around to pulling the transmission pan tonight....

The fluid smelled horribly burnt and was a brownish-red color. The trans filtering media was fully clogged from debris and particles. There wasn't noticeable metal flakes in the fluid itself, but the magnets were very full of various metal shards. Very small chunks of metal rod, metal shavings of various sizes and at the bottom of the pan there were a couple of small chunks of hardened rubber appearing to be what I would describe as chunks of what looked like some sort of main seal rubber. And the photos...

http://i999.photobucket.com/albums/af120/jquillia/Jeep XJ/null_zps39ddce24.jpg
The fluid...
http://i999.photobucket.com/albums/af120/jquillia/Jeep XJ/null_zpscaa6945e.jpg

Also, I realized that when the Jeep is running after about a couple minutes a grinding oscillating noise starts coming from the transmission at idle. Sounds like a lost cause and I didn't bother installing a new filter, gasket and fluid at this point, would it be worth a try or should I just move on? lol

 

[kastein]

I've seen worse, but that trans was FUBAR too... lol

Where does the noise come from, the front? It's probably the torque converter eating itself alive. Get the torque converter with whatever transmission you buy.

Oh, and flush the cooler lines and trans cooler on your jeep before plugging them into the new transmission. A lot of people forget that and give their new tranny a nice transfusion of metal shards and burnt fluid right off.

edit: here is the last AW4 I completely killed.


That noise was coming from the bellhousing, from what I can tell, the torque converter lost at least a few impeller blades and got them wadded up inside itself till they shredded. It wouldn't move in any gear. Fluid looked about like runny antiseize with the same kind of crap you saw mixed into it.

 

[QuillsXJ]

Hey Kastein, I honestly can't tell for sure where the noise is coming from. It does sound like it may be bell-housing though because it sounds like it is occurring in a larger open space. It could be torque converter. At this point I am looking for a replacement since a new converter costs just as much as most of the full replacements I have identified. I am thinking of possibly purchasing this trans off of Craigslist or at least taking a look at it: http://sfbay.craigslist.org/eby/pts/3815236960.html

I have a question and not that I am necessarily going to go this route, but I am curious: if I were to buy a year 98+ 4wd trans would I be able to unbolt the t-case and swap on my busted 2wd trans tail cone/driveline with electrical connectors? Basically, what is involved to convert a 98+ 4wd trans to 2wd to fit my application? Thanks!

 

[kastein]

You wouldn't be able to - the 2wd have a longer output shaft and it's got 27 splines instead of 23 and is a different diameter. Converting from one to the other involves a full teardown and rebuild basically since the rear output shaft is about the first thing to go into the housing and conversely the last thing to come out.

The easy way is just to leave it as a 4x4 drivetrain with the transfer case present and swap the rear driveshaft as well. That's literally all there is to it, everything else simply bolts on. If you don't want to do that, you're looking at either rebuilding your transmission (not advisable, from what I'm seeing) installing a 2wd transmission or tearing apart a 4x4 donor and your 2wd transmission, buying a rebuild kit, and combining most of the 4x4 trans with a minimum of 2wd trans parts from yours while doing a full rebuild.

 

[QuillsXJ]

Well hot dang they don't make it easy...I am going to convert this project to a 4wheel! Wouldn't be worth calling a Jeep if it wasn't! I am talking to this guy and the trans sounds like a golden find too! Awesome!!

 

[kastein]

You don't have to do the conversion all at once, hell I started at the other end with my MJ. I drove it around for a year with a dana 30 front axle and a 2wd transmission.

Doing it the other way (trans tcase and rear driveshaft first) is simple and then you can just leave it 2wd until you happen upon a d30 with the right gears and feel like finishing it. You'll even have 2-low until you put in the front axle :gee:

I am not sure I would pay 180 for that unless it has the transfer case as well, though. I don't know california parts prices, but you should check out the classifieds section of the socal chapter forum on here, you may find a better price.

 

[QuillsXJ]

The guy apparently has the transmission that I will pick up this weekend, but he said he has an unknown year transfer case unbolted sitting beside it. What years and model T-case should I be looking for to build this right to have my wiring plug in nicely with this year 2000 trans?

 

[QuillsXJ]

The Jeep drives!! Yesterday I bought the yr 2000 AW4 off craigslist and the guy had a late model np321J transfer case with rear driveline attached that I bought also. He threw in a spare AW4 valve body that he claimed was in perfect condition as a bonus. All for $330.

 

[QuillsXJ]

Since I had my 2wd AW4 pan and filter already pulled off I decided it was worth a shot to unbolt the valve body and try out the replacement that the guy gave me. I gave the pump pistons a full cleaning and installed it and the jeep drives and shifts perfectly! Very relieved!