Can you please let us know what fixed it?
Hi, regarding your post 2 months ago about your ZJ code p0740, did you find out what it was? Mine doing EXACT same thing and I need to back up what my mechanic is telling me.
On mine, I am being told that the Torque Converter went bad (causing code p0740, which detects TC lockup based on RPM/speed differential) which then caused debris to plug the Tranny Cooler causing it to heat up (causing same as your second code), and also causing the tranny to enter limp mode where it won't shift into overdrive (your third symptom). Perfect match to your symptoms.
My mechanic is hinting that I need a tranny rebuild because of the debris (almost $2,000), but I am finding it hard to believe since it drives so well otherwise.
My thoughts were that it's just a solenoid, that the overheating part isn't enough to outright pronounce that there's debis throughout the tranny and it needs a rebuild.
Besides, the torque converter itself didn't blow out, just the clutch portion (drives perfectly otherwise except no lockie on the TC on the highway) so at worst there's clutch material blocking my tranny cooler and that material isn't likely enough to require a tranny rebuild, right?
Any pros out there with some advice for me? Any chance the original poster will see this and let me know what their problem was?