aw4 doesn't like the cold.

I'm hoping that the answer to this not "new/rebuilt trans".

Anyway, I've owned this '90 for 10k miles. Paperwork shows that the trans was rebuilt 15k ago. A problem showed up late last winter that perplexes me. Above 60 degrees, the trans works the way it should... more or less. It seems to start in 2nd gear a lot and the torque lock jumps in and out a bit and unlocks completely after about 5 hours on the freeway.

We will assume that is normal for now.

Below 60 degrees, the trans will work 'normally' for about 3 minutes. After 3 minutes, if I stop and the trans has to down shift, it will drop into 1st and stay there unless I shift into 1-2 in which case it will then work 'normally' in 2nd. Otherwise, after about 5 minutes, it starts to hunt between 4th and 3rd, then between 4th, 3rd, and 2nd, then between 3rd, 2nd, and 1st, until it stays in 1st...unless I shift into 1-2.

After about 10 minutes, I can shift into D, and the trans will work 'normally' again for the duration of my drive. If I stop the jeep and the trans stays warm then I'm golden. If it cools back down to 60 or below, the process starts over again.

So far it hasn't been a big deal because most of my driving is within a few miles or I just take back roads for 10 minutes then hit the freeway but I'd like to fix it so it works consistently.

Any ideas?

I might add that a few days ago I noticed that if I start the jeep and run it long enough to get it to stick in 1st, then stop somewhere for 10 minutes or so, it will work normally once I get back in so apparently it doesn't have to be running, just warm.

Well there is always the possibility that the tranny is bad but I would check the TPS as that is what controls the tranny. I had a similer (sorry my spelling sucks tonight) problem on a 90. Had replaced TPS and adjusted it with an aftermarket part. Didn't work. Got one from a dealer and whalah! It worked fine.
Search TPS for adjustment and replacement.
Good luck!

Thanks for the response. I've checked the TPS several times in the past hunting down other gremlins and it seemed to be fine but maybe it's quirky that way. I seem to get a very random hard start/high idle thing as well but if I wiggle the wiring harness for the ECU, it goes away. It's the temp/3 minute threshold that stumps me.

Verify that you have the correct type and quantity of fluid in the tranny (Dexron-III). You might also check that the throttle body to tranny cable is properly adjusted. It doesn't affect the shift points, but does control the hydraulic pressure and being way off can cause very slow or no shifting.

thanks Lawson. I try to check the cable every time I open the hood. I took a sharpie and made alignment marks the last time I adjusted it just to see if it ever moves. I haven't looked at it in quite a while.

I guess a fluid change can't hurt either. I just wish I would think to do it before it turns 35 degrees.

Look for bad grounds, take all of them loose and clean them. The one going from the firewall to the rear of the head drivers side is a big culprit to electrical issues with the RENIX models. There are 3 grounds at the dip stick tube hold down bolt as well so clean them. After that pull each connector one at a time and clean them/lube them with di-electric grease. Even if this is not an electrical issue you have at least eliminated those normal RENIX issues.

Check your tranny cooler lines for kinks as well and change the fluid out for some Dex3, chances are it has the wrong stuff in it.

On our ZJ with 4.0 and chrysler auto [the wifes] there is a procedure to adjusting the kickdown cable that involves loosening it then tightening it, don't know if the XJ AW is the same, it may not have been put back in correctly when it was rebuilt.

I also discovered last year after it got cold that the tranny did not like being 1 pint low either, it made nasty noises on start up and ran funny, added that pint and it's been fine ever since, now thats the chrysler tranny not the AW4. All the other jeeps in the family are 5 speeds.

passages in the valve body can get varnish built up in them that will soften with heat and allow greater fluid transfer. You may be dollars-to-doughnuts ahead by running a product like Trans-X through it for a couple heat cycles and flushing the fluid. If the fluid is even remotely questionable, pull the pan, change the filter, and refill with Dexron lll.

A rebuilt transmission can "burn" the fluid very quickly if the cooler is not up to the task of removing the extra heat generated by tight tolerance break in as well.

I would drain and refill with dex III and half quart of lucas trans fluid conditioner. Mine was working ok, but I would lose 1st after it reached operating temp. I could manually shift into first no problem, but it would not grab first automatically... drained the pan, refilled with fresh dex III, topped of with lucas, shifts perfectly now.

One of the trans solenoids perhaps? Sounds kind of suspect w/the shifting and TC lockup giving you issues.

A fluid change and some conditioner for this weekend then. I hope it's not a solenoid, I just had all of those bench and drive tested by a jeep dealer up in Denver... or so they say.

No matter how smart I may think I am, my jeep always finds a way to bring me down to earth. My trans dipstick is difficult to read in the best circumstances so the level is always kind of a guess. I drained the fluid measured to about 2 quarts less than what it took to fill it (at least acccording to that dipstick).

I was also poking around the grill and noticed that the external trans cooler wasn't hooked up to anything. There were hoses but where it was supposed to be spliced into the trans line, it was blocked off and only the radiator trans cooler was hooked up.

I removed the external cooler and there was a solid wall of dirt packed between the cooler and the ac condenser in front of the mechanical fan which probably explains why my electric is constantly running.

I think I just solved 4 issues in one hour. 5 if you include my jb weld fix for the console door breaking off the hinge.