I would suspect the key cylinder. Ign switch normally would not keep the key from turning like that. You either have a bad cylinder, or a problem with the rack/pinion mechanism. Either will require steering wheel removal to diagnose.  

Joel Adams
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Well my friend, on those cars there is a theft deterant located on the steering shaft. It is connected to a cable that lines up the shifter and the ignition. The shifter needs to be completely in park, or reverse for it to work. Try wiggling the shifter and turn the ignition at the same time. It is on both auto and standard transmission cars. They need to be adjusted to align over time. I'm not good at sending pictures on this site, but a O.E.M. assembly manuel may help you figure out the sequence.

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Thanks, is this the interlock system you are referring to, with the wire from the transmission to the steering shaft, which requires it to be in park to turn key into LOCK position? I have had others also mentioning that, but it would not stop you from turning off the car. 

Thanks Adam, Yes I think you are correct. I have started to disassemble the steering column. Hopefully I just need to replace the ignition lock. 

I believe it's the rack assembly inside the steering column. I've never had one lock up but have had them strip. It may have a piece broken off and jamming the assembly. As others have said, the steering wheel must come off to inspect. The part on the lower left in this picture is the rack the others have talked about. On the end of the lock cylinder is the gear that goes this up and down.. I'm trying to find something a little better than this to help you out. 

Good luck to you!

 Reid

www.wildbunchcarclub.com

Count your blessings, though---

Saturday my whole steering column rotated about 270 degrees when I was making a turn-- column is completely broke and zero steering control.  The 'key cylinder went from normal 3 o'clock position to 9 o'clock and then down to 6 o'clock !

I could take the key out but the engine was still going.  Had to unplug the ign wire on distributor to shut it off.    I count my blessings , though-- I came close but didn't wreck .  I couldn't get it up the driveway into garage after I got it towed-- no steering...  I gave up on doing it myself and had Christian Bros. Automotive come pick it up and they're going to replace column.