Customer (name blocked for privacy);
IF you saw smoke coming from the column, then there is definitely an electrical problem there; smoke does not appear for no reason.
If your mechanic took the column apart and removed the electrical wiring and found no harness or connector problems, then the only thing left is the ignition switch itself. you may be able to verify this by removing the ignition switch and smelling it; usually when an electrical arc is occurring you can smess an acrid odor of burnt plastic. If your ignition switch can be opened and disassembled, you may be able to see a heat damaged internal contact. If your vehicle has a combination switch assembly for the turn signals, headlamps, washers, etc... this is also a potential source of the arcing and smoke.
If no obvious fault is found but the arcing and smoke recurs, I would suggest replacing the switches and the column wiring harness as a preventive fix; electrical arcing can cause a fire, even when the vehicle is off and unattended.
It would also be a good idea to call your local dealer service department to inquire about any open recalls or TSB's on your vehicle related to these symptoms; perhaps you can get it fixed for free if there is a recall (for example, many Ford products a few years ago were recalled for free ignition switch replacement due to overheating problems).
I hope this is helpful; if so, an accept would be most appreciated! Thanks!
