ronjenx

In the two situations you described, did the engine rev freely as if in neutral? Or, did you feel the Jeep trying to move?

Xodius

It was acting like it was in neutral. It reved but didn't move. Even my wife thought it was odd as it was in gear.

SeanFagan

Samething happen to me on parking blocks too!!! It's basically like it has no power?!! I just backed up and nailed it!!

Freewill

ESP is the main cuprit. It starts applying the brakes on one or more wheel(s) when the computer thinks traction is lacking. I've read many times about JKs that won't move because ESP is trying to do all the thinking for the driver. The rig comes to a stop in sand or against a small obstacle.

Turning off HSA is just extra insurance to make sure nothing applies the brakes except your foot.