swamper

I have a 90 xj auto, about three days ago the tranny started to randomly downshift for a second or two then back up again. It doesn't do it constantly, but probably half the time I'm driving. I checked the fluid, it's fine. I plan on changing it and the filter anyway, any ideas if that doesn't work as to what else it could be? It isn't grinding, or making any weird noises, just shifting funny. Happens mostly when you get up to around 45-55mph, then it will downshift all of a sudden, then back up. Also needs a tune up badly(which i'm gonna do this week). Could that affect the shifting? Thanks.

heep92

wow i have the exact same thing happen to me every now and then
its not everytime i hit that speed range but occsionally it does that to me too
sadly i don't have a clue either so hopefully someone will chime in with some ideas

losingxinsight

45 is about where it shifts to OD for me, and sometimes I end up putting my foot into it a little much or a hill will make it downshift quick, but that's the only thing I could think of.

sv41878

Check for vacuum leaks, sounds like the auto kickdown has an issue. Vacuum leak is most common.

heep92

not to steal the thread...
and i apologize if this is a stupid question...
but where would you find the vaccum lines associated with the tranny?

sv41878

transmission and t case and followed into engine compartment. Depends on what it's function is.

heep92

alright ill check that out
and to swamper sorry for kinda hijacking your post hopefully you find out what causes yours because other than whats been suggested about the vacuum lines and then your idea of servicing the tranny i just kind of figured i'd live with it...i mean it is a jeep after all... haha