'94 XJ won't shift until warm.
 

I've posted this before but it's been awhile and since new people arrive daily I figured I'd try again as the situation is still unresolved.

Long story short my 94 XJ (4.0 auto) won't shift out of 1st gear until the engine or perhaps it's the transmission warms up a bit. Maybe a mile or two worth of driving. Just sitting and letting it idle and warm up has no effect on the problem so it's something temp related transmission wise. You can give it all the gas you want and the engine revs real high but you aren't really going anywhere because it's staying in 1st gear. Ruling out the trans can anyone think of any sensors that might cause this? I get no codes. A mechanic suggested the idle air sensor. I do have one of the '99+ intakes on my '94. I know there are 3 solenoids on this thing. Is maybe one of those faulty?

I have changed the fluid and transmission filter, adjusted the cable and swapped out the transmission control module and that had no effect. I am thinking it's not the transmission itself because the fluid stays nice looking and once it gets warm it starts shifting and driving normally the rest of the day. Any ideas no matter how odd will be pondered. Thanks :)

Have you checked the TPS?

could be a stuck solenoid, could be a faulty TPS that sticks when cold, or maybe an accumulator with a damaged o-ring that doesn't hold pressure until the transmission gets hot

a decent mechanic should have a good scanner (Snap-On or equivalent) and be able to tell what the TCU is seeing and commanding

Pardon my dumbness....what is TPS?

Throttle Position Sensor


https://cimg2.ibsrv.net/gimg/www.che...dae639dcdf.jpg

Accumulator? I know nothing of this. The only accumulator I know of is in the air conditioning system. Please tell me more. :)

TPS and all the other sensors up on the intake manifold have been swapped out several times but with ones from the salvage yard. Since I have a '99 intake on the thing I even went and swapped in the '99+ sensors thinking the larger intake manifold might have been messing with the old sensors. Nothing.

I was thinking of swapping all the transmission solenoids out but may just try whatever one kicks in first. It's definitely something to do with the temp of the transmission since sitting and letting it idle until the engine temp is higher doesn't affect the shifting problem..

Start with the basics. Idle until at normal operation temps and then check fluid level. use the "Hot" side for normal operating temp or just start it and then check fluid and use "Cold" side of dipstick. (do all fluid checks for trans while in the "Neutral" position)

Thanks. Been thru all the basics so now looking for something more uncommon. Fluid and filter are fine. Throttle cable etc is adjusted. I'm thinking it's more a sensor or a solenoid issue than an actual transmission one since the fluid isn't getting burnt and once the transmission warms up it works perfectly the rest of the day in city or highway use.

Maybe I should put a heater on the transmission pan. :icon_wink:

Now mine's doing it
 

We had the first cool (Almost cold) day of fall here and mine decided it didn't want to shift up into Overdrive until I got the overall Engine/Trans operating temp up to over 110-112 by doing some wheeling in low range for a bit. If I find something strange and unusual I will let you know what it is, could be what is also causing your issues :)

The OP probably needs to have the transmission rebuilt.

The bands may have excessive wear.

I know that you said you have checked your transmission fluid already but have you checked it when it was off? Or on? On while in neutral or on in park? Make sure you check it properly. Had this same problem before when I had my old Camaro. I was pissed that I tore the hole tranny out and started it up only to see that it wasn't shifting. Turns out I didn't add enough transmission fluid when I swapped out the tranny. I checked it properly and added the corrected amount and it shifted flawlessly. DO NOT OVERFILL. This will cause just as bad if not WORSE problems.

More info...
 

Cruiser54 shared some great information here:


https://www.cherokeeforum.com/f59/jeep-214338/


Worth looking into...

Did it ever shift right with a post 96 TPS? If not I might try to match the 94. Thinking there might have been a change...Idk. though. I would verify it's sending the proper info to the PCM before doing much else.

Radi has sold his Jeep and drifted away, but if you PM him he might chime in. I think he once mentioned you can unplug/disable the TCU, then see if it will shift manually to differentiate between a mechanical or electronic problem. Again, not sure there.

Interesting. I wouldn't bother rebuilding the transmission since the things got way to many other flaws. Considering it runs and shifts fine once it gets a bit warm would you still feel it is the bands? As far as I know the bands have never been adjusted.

If I recall right it would always have this problem in the winter and it would go away in the summer. But the past year or so it's turned into a year round problem. I shall attempt disconnecting the TCU and see what happens. :)