Ok, so I signed up here to see if any of you guys have had this problem.
My ''03 Ion II has, for the last year, been possesed by merciless demons.
It will, from time to time, and for no apparent reason, fail to turn over/start. Sometimes it lights and then stalls (as if the fuel or spark was cut) and sometimes I get absolutely no response from turning the key. The accessories (radio, lights, locks etc) are never affected. The engine just refuses to start or will die immediately. I have had it in the shop for a stretch of two days during which they tried a number of things, swapped parts and chanted fell verses, but never fixed the problem. The best they could come up with was a possible problem with the passive theft deterrent system (the car thinks I''m trying to steal it). It will happen 1 to 3 times a month and will always start after 2 to 10 minutes of waiting. Any thoughts?

Well, the key turn with no result is probably a defective/corroded positive battery cable. For some reason, if/when the battery leaks, it wicks into the cable underneath the insulation and eating it up kinda like a termite does to a 2x4 ...

on the ion 95% of the time you need an ignition swith passlock sensor is part of the switch