This saved me a headache - my neighbor was freaking out because his truck wouldn't start. He had swapped keys with his wife, after he took the truck to the dealer for an ignition issue. They had reprogrammed his key to work, but not his wifes. He neglected to tell me this upon coming over to see if I could figure out what was wrong, but this thread saved me from spending too much time on it.
2013 JKU Sport, billet, auto, 3.73, LSD, 315/75/16 Duratracs on MB 72, 10A springs, Bushwacker flatties
Sold - 2005 TJ, red, auto, 3.73, 33" Duratracs, 4" lift
Ice storm casualty in 2007 - 2003 TJ, green, auto, 3.73, 33" Duratracs, 4" lift