Jeep became undriveable while on the highway going approximately 55-65 mi/hr. No warning. Just seems to stop mid drive. I tried to accelerate and nothing. Jeep just coasted until it stopped. I previously had the transmission rebuilt, maybe back in 2008-2009. All was fine with the transmission & driveability since then. I'm not saying that it is the transmission, but the behavior was similar in the respect that it came out of now where & I couldn't accelerate. In any event, once I got over to the shoulder I turned the key off & tried to restart. Nothing. So I got it towed home. Very next day Jeep started up on it's own w/ the key. I was only trying to turn on the radio. Once it started up & attempted to move it, which I did about 50 feet before I reparked it. Haven't driven it anywhere else due to apprehension. What could've caused the 'breakdown?' Is there something specific that could've caused it or I should have it check specifically for? No codes by the 2nd day because check engine light disappeared before we could check it. Thanks in advance.
Lots of misinformation. The engine stopped running. That has nothing to do with the transmission.
"the behavior was similar in the respect that it came out of now where"
There's hundreds of different problems that show up unexpectedly so you can't draw any parallels from that.
The Check Engine light is only required to turn on when the problem detected could adversely affect emissions. There's over a thousand potential diagnostic fault codes and the light will not turn on for about half of them. You can check for codes anytime. You don't have to wait for the light to turn on. All we know for sure is since the light did turn on for a little while, there is a fault code stored in the Engine Computer.
"tried to restart. Nothing"
What does "nothing" mean? Did the engine crank but not start? Were there no sounds and no response when you turned the ignition switch to "crank"? Did anything else work like lights or the radio?