Hi folks.I've been searching for this issue now for some time through the forums and can't quite find a consistent answer. This seems to be an intermittent issue. I have a 96 jeep cherokee, automatic transmission. I'll be on the highway cruising at 60 mph or so and then all of a sudden it will just downshift on me to what seems like 3rd gear on its own and the rpms shoot up to 2500 rpms while just driving at this point 55-60 mph. I'll pull over to the side of the highway, turn off the ignition, then turn back on and drive off, shifting normally and staying in the appropriate gear. Any ideas and info would be greatly appreciated. !!

 

What are the RPMs at before this "shift"?
It might be the TC unlocking instead of a downshift.

I would also suggest adjusting the TV cable. It takes about 2 mins, and theres a chance it might be out of adjustment and telling the trans to downshift.


To adjust the TV cable you:
1: Push in and hold the release button
2: While holding in release button, push "conduit" in as far as it will go
3: Release button
4: Rotate throttle to WOT, some people do this with the gas pedal. Others do it from the engine compartment.
5: Hold at WOT for a few seconds, cable should ratchet out a click or two.
6: Your TV cable should now be properly adjusted, take it for a test ride.

Here is another post about it on NAXJA
http://www.naxja.org/forum/showthread.php?t=1015963

 

only going to 2,500 sounds like a TC lockup issue.......there is a Seperate solenoid in the trans for this.......You can OHMS test them at the TCU plug Which On your 96 is located under the pass side dash i believe.

 

before the downshift, my rpm's are at 2k while driving 65 mph, after this sort of downshift that it does on it's own, it will jerk a bit and the rpms will shoot up to 2.5 k at 65mph. Turning off the car and starting it back up seems to resolve the shifting issue though, so I thought it was some sort of sensor. Just to clear some things, I have also replaced the tps from a parts store and have taken it to a mechanic to do a tranny flush on it to no avail.

 

Sounds like a TCU/TC solenoid issue...

 

yup.........Ohms test them at the plug....10-15 OHMS should be it....one in my trans Read .065 ohms...so i removed all three and replaced them.

 

what do you mean ohms test at the plug? Which plug is that? Is there some sort of technical right up on how to test the resistance on the plug? sorry for my ignorance

 

http://www.transonline.com/transdigest/magazines/1997-10/Shift%20Pointers/index.html

post back your findings.....

 

Thanks for the info !! I will post my findings, as soon as it gets nicer out.

 

could be that .......rule everything out.....ive know a lack of exhaust back pressure so give the same kinda of random shift issues so just take a look at everything on that end too...

 

nss switch will also do this. if you havent cleaned it wouldnt hurt

 

well i tried the tv cable adjustment and it seems like is has a rougher shift between first and second gear now. I did an ohms test but i got a reading of 001 when i set the multimeter to the 2000 ohm setting, since that is the lowest setting on my multimeter and got a reading of 001.Does that even seem right? I will also check into the nss when I get a chance.

 

try pulling the brake peddle back with your foot
when it happens my brake switch was the culprit

 

that doesnt sound right...are you grounding your prob where you should be?

 

ok, so I ended up getting another multimeter with smaller probes and all three spots on the plug came in at 11,11,and 14. So does that rule out the solenoids? I tried the brake pedal thing and it didn't work, so I guess it rules that out. So the only thing I can think of now is to clean the nss or replace the TCU?? Is that right? And replacing the TCU, can I just swap it out from any auto trans cherokee at the junk yard?