Cold transmission wont shift out of 1st

How many miles on the Jeep and how long since the last transmission fluid change? That's usually my first guess and a fluid change cures most of these.

The TPS in the throttle body is notorious for getting a bad electrical connection that gets better as it warms up. I would use some spray electronic contact cleaner in it's plug and socket to see if it fixes it. We were told ours was 'dead' 8 years before we sold it and a clean every couple years kept it going strong.

The TPS controls shift points on the automatic.

Mike

I purchased it in late 2005 with 290K miles. It now has 320+K miles and I don't remember having the trans fluid changed when I bought it, so it's anyone's guess :/

Sticking valves/springs.

"Ewwwww"

Let's go back to step one.

Transmission fluid should be checked with the transmission warm, engine in Neutral (or as indicated by the sticker under the hood). ..needless to say, always set the parking brake or put it up against a curb especially if it calls for testing in Drive.. Always safer with two people.

Too much fluid is just as bad (and often worse) than too little fluid.

I'm betting it needs the valve body cleaned and flushed.

With that much mileage your best bet is to take it to a good local shop and have them drop the pan, tank the valve body, and replace/clean the debris filter. Keep in mind that there is no way to replace 100% of the fluid without dropping the torque converter. The closest you can get is a transmission flush, and that's not cheap. The alternative is to get a fluid pump and drain the transmission in a few hundred miles and refill with fresh fluid (pumps can drain right through the dipstick tube).

Quick test. Engine running, transmission warm. put it in Neutral. Use a stopwatch and time how long it takes between shifting to Drive and first forward move. Then do the same between Neutral and Reverse. N-D should be about 1.2 sec and N-R should be about 1.5 seconds max. Faster is better.

There is the "Ferrari tune-up" method. That's basically getting it up to a moderate speed then dropping one gear range. Be careful not to overrev the engine and don't do it for more than a few seconds. Get a feel for what speed in 2st is high rev, then go to that speed in drive and downshift. Do the same thing from 2 to 1.

That can move the crud along and out of the valve body.

Or just take a shot of spray cleaner to the TPS that controls the shift points... Quick easy and cheap and has been known to fix those symptoms on many occasions, even here in this newsgroup.

Mike

Both are probably good things to do (servicing the trans, and cleaning the TPS)...

The trans shifts well enough: neutral to drive is almost instantanious, and neutral to reverse takes to a count of "one thousand one" (at a natural speaking pace...didn't have a stopwatch handy...).

Thanks for the suggestions.

Sounds reasonable. Take a look at the linkage to the throttle body. The shift cable might be out of adjustment. Fairly simple instructions but hardly ever work as advertised.

Find the shift cable on the throttle body. There is a release button just where the cable holder mounts to the intake. Push in the little button so the cable moves and push the cable back into the sheath as far as it goes. Then open the throttle plate to wide open. The cable should ratchet. If it doesn't you have to play a bit with the adjustment till it feels right to you.