03 wrangler wont start

Have you lost the chip out of the key?? try the spare key before you go any further

check the ground leg to your engine.. it runs off the neg. battery terminal. will connect to frame and engine.. pull it off, wire brush it put it back.. you radio will work, 'cause it draws much less current, and is grounded in dash.

When this happens, move the Gear Selector lever a bit. It has a Neutral Safety switch that may be slightly out of adjustment

Hi Chris, Check the battery and terminals. Try a jump start and if that works replace the battery. Regards John

Have you checked your ignition coil and starter? If you have good battery and you can hear the starter turning but the engine itself wont turn over than you have a possible frozen engine? Check the block to see if it cracked? Check to see if you have an oil leak from the head gasket? Also if it has overheated this will also cause the engine head gasket to blow and seize up.

Pull off the battery cables from the terminals, take a bit of sandpaper, and run the **** over the terminals. Then, mix a 25/75 Arm&Hammer/Water mixture, take a rag, and run that on one terminal, then the other, try not to drip water. Take sandpaper again, and run it over the terminals again, until they are fully shiny. Now, do the same things on the inside of the battery connectors. Make sure they clamp down well. That should do it. If not, make sure all the wires are good and solidly connected. Finally, get a voltmeter, and test between the block and the positive connector/terminal. Should read ~12.4-6V. (12.4 = bit low, but I figured if it's trying to go through a corroded connector or a short, it will be a bit low)

Check engine block ground.
Check starter.

First, make sure you can turn the engine by hand. If you can't then the starter can't turn it either. Have someone else turn the key and look for the source of the click...may be a relay. Go over the starting circuit with a volt meter. Check for power at the starter main terminal and then with the key turned to "start" check for power at the trigger terminal on the starter. Check battery voltage and check relay operation.
You have a neutral safety switch on the transmission if its an automatic and a clutch switch if it's a stick. Check them as well. Make sure battery grounding on fender and block are also clean and secure.

ck the engine to body ground.located back side of engine and srew to firewall.

Sounds like an antitheft problem I would start with the antitheft system. Usually when you only have one key all keys have to be programmed together even the original. When you have more than one it is easy to program additional keys.