Wont shift into overdrive (NEED HELP)

I just bought a 2000, 4.0, auto, XJ with 168.000 miles on it. The vehicle is in fairly good physical shape; however, maintenance was seldom performed other than changing the oil. So to make a long story short, the transmission fluid doesn’t look like it has ever been changed. (Yes, the trany fluid is dark brown, basically the color of used motor oil). I bought the Jeep knowing the problems; although I didn’t mind paying a fairly small price for a fairly nice XJ. I tried doing a search and found that one possible problem could be a bad throttle position sensor. What other possibilities are out there? Also, what are the chances that my Trany is going bad and my OD is toast?

Try several fluid transfusions, 3 quarts at a time, using the drain plug on the pan first. Use Dex III. That may be all it needs.

Also it may be the TC (torque Converter) lock up that is missing, not OD. I find it hard to tell the difference. Both are operated by electric solenoids. There are several threads here on the tranny, it is an AW4. Do a Google search for "AW4 naxja.org shift XJ" and it should send you right to them.

I had this problem too!!

Turns out it was just the Tranny control module had popped a fuse some how!! Put a fuse back in and it was like new!

Check the passenger side kick panel for the fuse!

Thanks everyone for your suggestions. I’ll start trying each suggestion tomorrow.

Ecomike said:

Try several fluid transfusions, 3 quarts at a time, using the drain plug on the pan first. Use Dex III. That may be all it needs.

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Last night I completed my second drain and fill with Amsoil ATF. It’s hard to believe, but my overdrive is now working!!!!!!!!!!!!!!!!! It already shifts sooooooooooooooooooooo much better! I've used a total of 7 quarts so far, and I will probably add another 3 quarts tonight.

I'm running 2,500 RPM's at 70 mph.............does that seem correct?

Seems about right for stock gearing.

the_weirdo said:

Seems about right for stock gearing.

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X2, I have the same numbers, your right on the money. I got the same results on my daughters 89, 3, 3 quart Dex-III, transfussions did the trick, abour 12,000 miles ago.