I have the same problem with my 2008 . Just put it in neutral and it should start. Seems to be a problem with the "Range Switch" ( neutral safety switch ).

 

Yea unfortunately for me I purchased a new starter for it.

 

I have a friend with a 2010 Grand Cherokee with the same issue, start sometimes, delayed start, etc. After multiple trips to his local dealership, went to another dealership and found out that the starting problem was a well- known issue and that the JGC needed a new TIPM. Installed the new TIPM and everything has been fine since. This was about 6 months ago. Possibly could apply to the wrangler as well.

 

Mine does the same thing. Haven't seen or tried the ground wire fix but going to. After reading a bunch of threads and checking mine out it is the neutral safety switch. Move the shifter around. Even move it from park to neutral and back again. It helps me. For. What I have read it costs a butt load to replace the switch and it usually doesn't last long.

 

Ground wire from chassis to alternator bolt, also install a 4 gauge wire from negative post to the chassis, jeep grounds suck donkey balls.

check that your positive and negative battery terminals are real tight. Pull the tightening bolt of the terminal out install a couple of small washers then re tighten, the stock set up does not let it tighten all the way. Mine did this it fixed the problem. Do this for both terminals.

Lots of people say jiggling the shifter is an issue.

 

Won't be able to try this fix for a while however ill give it a shot when I can and report back.