All,

I have had an ongoing issue with my 97 XJ where the torque converter will unlock in OD while driving and will not relock until I stop and let it sit for some time. Now, the TC will ONLY unlock in OD, no other gear. I finally figured out what the trigger is to unlock. When I let off the gas while driving down the highway and get back into it is when it unlocks and will not relock under any circumstance. I have since replaced all of the shift solenoids, the TC lock up solenoid twice and replaced the trans control module with JY one. After all that, I still have the issue. I get about 10-15 miles of normal driving on the highway and as soon as I let off the gas and get back on it I notice my RPMS are much higher and the CEL comes on.

NOW, what else could cause the TC to unlock like that and it ONLY happen in OD and no other gear? The local AAMCO is telling me I might need a new TC. Please help!!

 

Replaced the TPS and still nothing. Im really finding it hard to believe this damn thing needs to be replaced if it only unlocks in OD and NO OTHER GEAR!!! Any Help?

 

Have you adjusted the kickdown cable?

Other items in play are the TPS, VSS, brake pedal switch, and the NSS. Someone else here had a TC lockup issue and resolved it by cleaning the NSS and making an adjustment to put more pressure on the contacts, IIRC. Someone else mentioned cleaning the 7 pin and 8 pin connecotrs near the trans dipstick and coating them with dielectric grease.

 

Any resolve to this issue? I may the same problem. Initially I thought my overdrive was not engaging after a while, but this tc lock up is a new approach.

 

Have you solve it ? I have the same issue

 

Interesting.
I have somewhat similar condition in 89 XJ where the torque converter will unlock whenever I ease off gas pedal just slightly, while driving in OD at around 35 - 45 mph speed. This is not a big issue, but obviously it should not behave like this.
Otherwise the AT works perfectly.

I have checked and adjusted TPS couple of weeks ago to the proper specs. (It was off specs quite a bit, but it made no difference to this TC unlocking issue at all)

 

Interesting! I have a 1994 XJ that may be having TC issues as well. Unfortunately, theses issues started more frequently after I swapped the engine to a 96'(mechanic buddies did the swap). Now my jeep is Randomly holding
hostage any gear it wants (mostly when cold) I can get stuck in second and rev the engine and not really go anywhere until I rev high enough for it to change gears. I have put 90 percent of my focus on the throttle valve control cable.
I adjusted it several times and once in a while I get it just right and the truck shifts like a demon! So I really feel that is the issue. I ordered a new one since the clamp on the old one is shot. I hoping that it will make the difference
when I replace it. I don't think the trans is bad at all just set up wrong somehow. I have been worried about the TC also. When they swapped in the 96 motor they changed a lot of things...I have to go over it more. I will update you if my
TCV cable fixes the shifting,,,, super annoying. ///And this is my first post here! Haha Hi everyone!

 

Ive tried everything you guys have mentioned before. Kickdowns, TPS, blah blah. I have to give the short version now as I have to go to work, and I am barely on here. But it turned out to be the signal getting lost between the transmission control module and the solenoid itself. More than likely both are good! Its the resistance on the wire loom that runs along the passenger side of the engine, opposite of the exhaust, and down through the little pass of the firewall and the tranny bell housing. I cant remember ohm specs on those wires, but when they heat up tge resistance increases blocking the lock up signal. Which of course cooks the tranny causing more heat. I picked up a wire loom heat shield from an LMC truck catalog, used an electrical connector removal tool and pulled the wires out (remember which wire goes where) and ran the heat shield wrap down the length of the wires. It's probably a best bet to replace the wires while youre at it since theyve been exposed to that amount of heat. I connected everything back up and I havent had much of a problem ever since. I stress MUCH. It did show back up again, but only when I was driving like an *******, having to pass a slug down the road and had to accelerate at full throttle for too long. I also added a manual transmission lock up switch to my TCM. You can search for the specifics on that. It seems difficult, but it's broken down very thoroughly and is very accurate. After those two, Ive never had a problem locking her up ever since. Ive been through 3 transmissions chasing that issue. I hope this will save you guys as well.

 

Here's one link for some TCM (TCU trans control unit whatever verbiage same stuff)
https://www.naxja.org/forum/showthre...shifter&page=2

Heat shields for wires (not exactly what I used, but does the same job)

 

This is the very last thing I’m down to trying to fix this same issue. No CELs, good transmission fluid color and smell, tested every pinout at the tcu, and cleaned every transmission-related connector in the engine bay. Has anyone else done this that knows the best way to feed the heat shielding over the wires and the wires to put the heat shielding on?