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Bad Transmission

WA-4x4

NAXJA Forum User
Location
Puyallup, WA
I have 96 XJ with the 4.0 and the auto trans is bad. I can't afford to rebuild so plan on buying a used one and have a few questions. What year transmissions can I use, can I use a TJ or one of the Grands, or are there any other rigs I could pull the trans from?
 
I believe you can use some of the 93 Grand transmissions (4.0L only, make sure it's an aw4 tranny before buying) but none of the TJs. Could be wrong.

As for XJ donor years, 91 through either 96 or 97/98 (not sure) should be bolt-in, you may have to swap some sensors out. 99 and later should be bolt in I think but you might have to swap even more sensors out. Make sure you get one from a 4wd XJ if yours is 4WD, and don't go 90 or earlier because those have a 21 spline output shaft which means you will have to change the tailshaft (i.e. pull the whole transmission apart) or swap transfer cases as well.

I am going through this as we speak, I'm working from home right now and have a new transmission out of a 98 sitting in my friend's MJ, going to put it in my 96 XJ tonight hopefully. I'll let you know how it goes.
 
I have 96 XJ with the 4.0 and the auto trans is bad. I can't afford to rebuild so plan on buying a used one and have a few questions. What year transmissions can I use, can I use a TJ or one of the Grands, or are there any other rigs I could pull the trans from?

So whats wrong with the tranny? Keep in mind that it's electronically controlled, so bad or incorrect shifting is probably not a mechanical problem. Often its a bad solenoid.

For swaps, I'd look for 91-96 XJ donor. 1997+ had some sensor changes. You can use the newer one, but it will require pulling the tailcone and swapping over rotor and sensor from your old trans (unless you like it upshifting at 1/4 the normal rpm). The newer tranny will also have an extra sensor up front that you can ignore.

have a new transmission out of a 98 sitting in my friend's MJ, going to put it in my 96 XJ tonight hopefully. I'll let you know how it goes.

Have fun with it. See above about swapping the rotors and the output shaft speed sensor. There is a writeup around here somewhere with pictures.
 
Thanks for the heads up on that, I was going to say - I saw you post about the output speed sensor saying you had built a small circuit to simply divide the number of pulses from the sensor by 4, so I figured something had to be changed out, or I could spend the evening hacking up a TTL board with some flipflops on it or something. Didn't remember enough specifics to actually figure out which sensors were the ones that needed changing, or which years they changed over in though.

Not sure about WA-4x4 but my transmission is doing some really funky stuff. It randomly unlocks the TC or slips the clutches (not sure which, I suspect the former) which seems like either a fluid pressure issue or an electrical issue. It also overheats quite often, lurches while shifting occasionally, and on Saturday third gear disappeared and it went into limp-in mode, leaving me with only first (or second, I forget) gear working, and even that was starting to slip badly by the time I got home. It's been abused though, I had been half expecting this for months - the previous owner never changed the fluid in it, and it had been starting to randomly slip severely if I got off the highway and it got even slightly above nominal temp.
 
Thanks for the heads up on that, I was going to say - I saw you post about the output speed sensor saying you had built a small circuit to simply divide the number of pulses from the sensor by 4, so I figured something had to be changed out, or I could spend the evening hacking up a TTL board with some flipflops on it or something. Didn't remember enough specifics to actually figure out which sensors were the ones that needed changing, or which years they changed over in though.

Not sure about WA-4x4 but my transmission is doing some really funky stuff. It randomly unlocks the TC or slips the clutches (not sure which, I suspect the former) which seems like either a fluid pressure issue or an electrical issue. It also overheats quite often, lurches while shifting occasionally, and on Saturday third gear disappeared and it went into limp-in mode, leaving me with only first (or second, I forget) gear working, and even that was starting to slip badly by the time I got home. It's been abused though, I had been half expecting this for months - the previous owner never changed the fluid in it, and it had been starting to randomly slip severely if I got off the highway and it got even slightly above nominal temp.


Make sure you're got Dexron in there and not ATF4+ as that can cause slipping and overheating. On the later models, I understand a dirty NSS switch can cause the t/c to sporadically unlock.

Here's the schematic I used for my converter.
http://mysite.verizon.net/~chris83803/AW4_Sensor_Converter.pdf
(writing on left says input ranges from 0.1 volt to 30-volts)
http://mysite.verizon.net/~chris83803/board.jpg
http://mysite.verizon.net/~chris83803/box_mounted.jpg

I used a CD4013 flip-flop as a divider and a quad op-amp for cleaning up the input. All parts were out of my spare parts pile. Not too bad for an amateur. Someone else built one using my sketch and said it worked great.
 
91-96 XJ 4.0L I think for plug/play. Possible early 93 ZJ 4.0L. Possible 97-01 4.0L XJ if you don't mind swapping the gear selector switch and cutting/splicing your old trans wiring connectors on and not using the input speed sensor used on mid-98 and up.
 
My trans will work fine around town and on the freeway until it heats up, then it will downshift. Then if it gets hotter it will downshift again. The fluid is black and the guy i took it to said something in the torque converter burnt up sending crap through the rest of the trans.
 
Make sure you're got Dexron in there and not ATF4+ as that can cause slipping and overheating. On the later models, I understand a dirty NSS switch can cause the t/c to sporadically unlock.

Here's the schematic I used for my converter.
http://mysite.verizon.net/~chris83803/AW4_Sensor_Converter.pdf
(writing on left says input ranges from 0.1 volt to 30-volts)
http://mysite.verizon.net/~chris83803/board.jpg
http://mysite.verizon.net/~chris83803/box_mounted.jpg

I used a CD4013 flip-flop as a divider and a quad op-amp for cleaning up the input. All parts were out of my spare parts pile. Not too bad for an amateur. Someone else built one using my sketch and said it worked great.
Awesome, thanks a lot! Yeah, I have Dex III / Merc in it. Fluid was really gross when I did a drain and fill a month or two ago while replacing my cooler lines.

My trans will work fine around town and on the freeway until it heats up, then it will downshift. Then if it gets hotter it will downshift again. The fluid is black and the guy i took it to said something in the torque converter burnt up sending crap through the rest of the trans.
Exactly the same here, except for the freeway part... instead of downshifting mine just slips, goes open, and I hit the rev limiter if I'm not keeping an eye on it :roflmao: Nothing like hitting the rev limiter at 80mph in the left lane to get your attention.

You should change the fluid before you do anything. That might solve your problem.
Agreed. It made mine better, and probably prolonged its life slightly, but didn't end up fixing it. Sounds like WA-4x4's is in better shape than mine was because it hasn't started really really slipping yet.
 
You should change the fluid before you do anything. That might solve your problem.

Yeah, flush that puppy, unplug the TCU and then test drive it shifting manually to see how the hydraulic/mechanical parts are functioning.
 
Just realized I hadn't dumped this info here... someone in another thread posted up a Pirate link about rebuilding the AW4.

Info on rebuilding:
http://www.pirate4x4.com/forum/showthread.php?t=690054
Source of rebuild kit:
http://cgi.ebay.com/ebaymotors/AW4-...r_Truck_Parts_Accessories?hash=item4a8e93a700
Front pump seal, if it doesn't come with that kit, is a NAPA 1-5235, pan gasket + filter kit is an ATP B112, rockauto's price on that is half of NAPA's price so I'd go there.

So if you do need to rebuild, you can... or you can just put in a used one and hope for the best, if it works it'll probably be faster than rebuilding. Keep the old one around and rebuild it if you feel like it or end up needing to.

EDIT: front pump seal does come with that kit, it seems.
 
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