skarpenz

Lately when I'm driving for more than 20 mins at a time my jeep will seem to come out of lockup in overdrive. I'll be cruising at like 65 and the rpms will climb a little and OD doesn't seem to be fully engaged. When it does this and I give it 1/4 throttle the rpms will drop down a little and lock into OD but as soon as I let up on the gas it goes back to higher rpms. The other day I was driving and messing with the OD a little and it downshifted into 3rd and would not go back into OD at all. I pulled over and turned the jeep off, cranked it back up, drove it and it shifted FINE. Ran in OD perfect for about 15 mins and went back to messing up. It usually runs fine before it warms up, or the first 15-20 of driving it.

At first I thought it was the beginnings of catastrophic transmission failure but now I'm thinking its more along the lines of an electronic problem. Its the original AW4 with almost 170k miles. Any clue as to what might be wrong?

BlueXJ

You are approaching the 180,000 mile point at which the TPS often goes out. It is a reostat and the cruising point has the wiper inside wearing at that point. So eventually they carbon up or just wear a flat spot on them and the tranny info is directed through the TPS to the TCU portion of the computer. The quick and easy part is you just have to replace the TPS on yours as it is a OBD Jeep. Two screws and you are home free.

mike

+1 on what blue said i had the same problem, put on a new TPS and shifts into OD and now stays there.

skarpenz

Thanks a bunch guys, I'll replace it tomorrow at work. Anyone want to buy a Jeep? Haha.

BlueXJ

Put it in the for sale section.

skarpenz

I did. I've been trying to sell it for a couple months.

wewsel

Mine does the same thing first thing in the morning sometimes....6:00 am when I get off work, I'll start home and it will shift out of O/D within 1 mile from work.... but when I get in later in the day it does O/D fine.... only does this sometimes.... I know I have some trans problems.... I have to start off in 1st then put it in drive after I'm going........ How much does it cost to rebuild these trans? 2wd 98
Not complaining....I only paid $300 for it....

96 XJ Sport

I'm having the opposite problem that skarpenz is having. Mine will lockup just fine every time, but it will not unlock into 4th when throttle is applied to downshift. I have to keep pushing the gas pedal until it's enough to make it downshift into 3rd which is a fairly big jump in RPMs. Could this be the TPS as well? I'm at 133K.

skarpenz

Okay. I haven't replaced the TPS yet, but today the truck wouldn't start. If I give it some throttle then it will run fine as long as I'm revving it up. When I let off the gas it just dies instantly. This is probably the TPS as well isn't it? I guess the damn thing finally crapped out on me, haha.

96 XJ Sport

skarpenz, did you get your new TPS in yet and did it fix your problem? This is bizarre, but I replaced my TPS yesterday as an attempt to fix my opposite problem that I mentioned above, but there was no change. Then today, mine started doing EXACTLY what you stated at the beginning of this thread.

If the TPS isn't causing this, what else could it be? Is there something vacuum actuated maybe that tells the torque converter to lock up that could be leaking? Anyone?

skarpenz

Is yours not starting?

96 XJ Sport

Sorry, I wasn't completely clear. Mine is starting just fine, but it is popping out of OD just like you explained in your first post and will go back into OD when gas is applied, for me about 1/2 throttle. It is sporadic though, because it all worked just fine on my way home today.

mooky

I had a similar issue with my '04 WJ V8, VIN N. 6 months ago, I'd be rolling down the freeway, cruise control engaged @ 65-68 mph, and I noticed the RPM jump up a couple-few hundreds and come back down, I stopped using cruise control and the problem never occurred. 4 months ago, it started occurring without cruise engaged, engage cruise, and it happened non-stop. Last week it started occurring more frequently without cruise engaged. I replaced the TPS. Problem is gone. I Hope this helps someone.

jon with the jeep

i have had this exact problem for a while now.. did u fix it and if so what was it ive done fluid, tps, obd and nothing helps yet

Radi

Intermittent TCC lockup problems- if you have verified the TPS is operating properly and the tranny throttle cable is adjusted correctly....one more thing to check is the ground to the TCU and transmission case. Despite what the service manual says, the solenoids primarily ground through the case, not the wiring harness.
Black wire- D7 at the TCU should be ground. Check resistance from there to battery (-). If you see anything other than zero ohms, fix the ground.
Repeat from transmission case to battery (-). If it doesn't show zero ohms, fix or replace the ground to the tranny case.

Also- on (IIRC) 98? or newer the NSS comes into play, it has an added function of reporting what gear you have selected. It's not impossible that a flaky NSS could cause TCC lockup problems.