You would have to test the wiring at the electrical portion of the ignition switch checking for power transfer across the switch as it is turned and check for voltage drop due to resistance across the switch. Make sure all your connections are clean tight and secure. Try "jump starting" the Jeep and see if it starts of another battery. There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online