Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
2009 Honda Civic Dx with a 1.8 L engine was driving normal, shut off, and upon return about a half hour later, car would not crank. Headlights burn bright, does not dim when trying to crank. Tried to put in neutral to see if it would crank, shifter would not move(shifter interlock) No dash warning lights, horn and brake lights work. I am suspecting a bad ignition switch, but don't want to be a parts changer. Is there any other checks I can do to test the ignition switch?
Check the 50 amp MULTI-FUSE 2 (Under hood fusebox, left side of engine compartment)
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer." I have learned more by being wrong, than I have by being right.
I wouldn't even begin to diagnose an electrical problem without a wiring diagram. It's like trying to drive somewhere you've never been without a road map. You should be able to look at a wiring diagram and narrow down the possibilities making your diagnostic process quick and accurate.