I went to star the jeep and when I turned the key on everything came on like it should but when I went to start it nothing happened. At first I thought it might be a weak battery so I jumped it and still had to mess with it and move the shiftier a little bit to get it started. I tested the battery and it was somewhat weak but it still passed. I hooked the scanner up to it and got P0202, P0201, and P0204, wich was injector circuit/ open cylinder for cylinder #1,2 and 3. A P0141 and P0138 both were O2 sensor codes nothing new there, I also got a P0301 for cylinder 1 misfire and a P0700 for Transmission control system. I am thinking that maybe there is a loose connection on or in the transmission range selector that makes it think its in gear and not engage the starter.

 

If you have to move the shifter aroumd, it could be the NSS, or Neutral Safety Switch, that prevents the Jeep from starting unless it's in a certain gear. We just got rid of an '05 Grand Cherokee WK that had a P0700 and it said the computer "lost communication with the transmission".

 

When it happens, try starting it in Neutral. If that works, it's your NSS as stated above.
My son has an XJ this happened all the time, and the more he drove it the less it happened. I have a ZJ and every great once in a while it will happen too.