Originally Posted by holy_crap
Jump start or push start (if you have a manual) the Jeep. Then with the engine running, disconnect the battery. If the engine shuts off, probably means the alternator is bad and not supplying enough juice for a spark. At least that is what I was told to do years back with my old VW Beatle.
PLEASE DO NOT DO THIS!!!! Worst case scenarios include: battery blows up... You get acid in your eyes/skin, fry your PCM, blow other electronics, fire...
Test your battery and alternator with a multimeter. I like to test the battery after vehicle has sat overnight, test battery with vehicle off. Then start vehicle and test battery again, then put MM on alternator leads to see if it's giving you good voltage.