weird transmission shift

[wildcat-xj]

89 xj 4.0 4x4 auto

when cruising down the road in 2wheel drive between about 25 and 40mph, the tranny shifts up and down. i shift into the "3" position on the shifter and it still does it, so im guessing it is shifting between 2 and 3.

what causes this and how can i fix?

thanks! :wave1:

 

[joe_peters]

Well, the TPS, the throttle body pressure cable, possibly the tc unlock switch on the brake pedal, the TCU, soleniods, fluid.

Start with the basics. Check the fluid level and condition. Check/adjust the TPS, adjust the throttle body pressure cable. If no change, pull the TCU's inline fuse or simply unplug the TCU and see if it shifts manually Ok, this will eliminate hydraulic/mechanical issues.

Post back what you find.

 

[kastein]

Are you sure it's 2 and 3? It could be 3 vs 3 w/ torque converter lockup, but I'm no transmission expert so I could well be wrong on this.

 

[*89Laredo*]

Mine unlocks the TC between 30 and 35 If I hit a bump, etc in "comfort" mode. Sounds like its constantly shifting.

What position is your switch in? If its in comfort, try power and see if it still happens.

Easy to do and free, its worth a try.

 

[wildcat-xj]

well, got the shifting issues fixed. this weekend magimerlin hooked up his renix scanner to the heep and everything was running within good numbers except tps. we adjusted it down to correct numbers. then he pointed out the tranny switch on the dash. I dont have one. Seems the po's mechanic put in a defroster/rear wiper dash panel and plugged them in. so to change the tranny shifter thing i have to turn my rear defroster in.:roflmao:

i have 2 defroster switches...

looks like i will be looking for the correct dash panel next time i go to the junk yard.

thanks magimerlin!!!!!!:wave1::thumbup::wave1::thumbup:

 

[joe_peters]

So, if you "defrost" your transmission it works correctly?

 

[wildcat-xj]

So, if you "defrost" your transmission it works correctly?

basically:roll::roll::roflmao::roflmao:

 

[iwannadie]

Mine unlocks the TC between 30 and 35 If I hit a bump, etc in "comfort" mode. Sounds like its constantly shifting.

What position is your switch in? If its in comfort, try power and see if it still happens.

Easy to do and free, its worth a try.

Not to thread jack...

Is that normal behavior for the TC to unlock and lock at those speeds? My 97 does this at that speed also. One road I drive has a 30mph speed limit so I'm right between 30-35 and it's like I'm always shifting. Cruising any other speed things are perfect.