2002jeep wrangler battery drains overnight

Overnight complete discharge would imply a relatively large load such as headlight or interior lighting.

Check the vehical after dark for unexpected lights.

Be sure to unplug any added accessories, USB chargers, etc.

If nothing found, suggest using a clamp on amp meter and check for excessive drain. Parasitic load (sleep mode) of modern vehicals should be less than 75ma.

Check The Wheel Sensors And Wiring And Plugs Check with A VOM (voltage ohms Meter) for shorts etc.
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Probably your battery needs to be charged or changed. Why don't you try another battery in it and see what happens

I have done this before, put about a 10 amp charger on the battery. Pull the courtesy light fuse first. Look at the battery charger, it is probably charging several amps, pull one fuse at a time. When the charging amps drops down you found the fuse the controls the problem. I had a car several years ago that someone pulled the seat belt all the way out, somehow it was pulling a load and draining the battery overnight.

If the battery seems ot drain overnight it is confirmed that there is a drain on the electrics/electronics circuit of the car.
Please click on the link below for tips:

http://www.fixya.com/cars/r5824824-draining_car_battery_charge

I had the same problem with my 08 Wrangler, the forums I checked out suggested disconnecting the battery for ten min and then reconnecting. It was also suggested that it may be caused by a moisture problem (damp interior) so I sat a bucket of moisture-sorb on the floor overnight. After reconnecting the battery the problem was gone, try it and see if it works.

Does it act like a dead battery? An electrical component could have been left on and drained the battery. If the battery is in good condition it should be rechargeable. You didn't mention if it didn'tcrank, cranked slowly, or cranked and just didn't fire.

Alternator. The regular inside the alternator has an open diode. Disconnect the battery overnight and it will start the next morning. The alternator will need to be replaced to fix the problem.

If you hear the pump running when you turn the key on, likely it's good. It can drain back while sitting overnight but so can a bad injector (testing necessary)
Two years may be a long time if wires are not good quality check them as well as cap and rotor. If fuel filter is old, it may need to be replaced.
Careful testing is important, especially with the amount of expensive electronic controls on your engine. That's why good shops invest thousands of dollars in equipment and don't employ psychics instead. The best you can do without such equipment is to determine if you have fuel and spark when it's not starting, then find out why whatever is missing isn't there.

Check your battery status in the morning. Sounds like you have a drain, or a weak battery which will cause the problem.