The jack location on a 2003 Jeep Wrangler depends slightly on the trim level and whether it's a two-door or four-door. However, it's generally located underneath the vehicle, behind the rear passenger seat.
You'll likely need to remove the cargo cover or some sort of access panel (often a panel held in place by some fasteners) to reach it. Check your owner's manual for the precise location and instructions on how to access the jack and spare tire.
