I just purchased clean 2003 Chevrolet Monte Carlo LS aware of pass code security system. I was going to store and doc visit I am stranded. I replaced new ignition and switch how ever the learning not working.

Any help would be great

 

This is where I GM has failed, as the shop manual does not have any diagnostics to troubleshoot a failed passlock system and the GM Tech II scan tool is unable to tell you anything about the reason the car went into theft lock.
The system relies on a code that is synced between the chip on the lock cylinder (not the ignition switch, the lock cylinder in the ignition switch), the BCM and PCM. The learn procedure (which is also used to exit a suspected theft event) can be tricky. A common mistake made is removing the key from the lock or not waiting the full time for the "security" message to stop displaying before attempting to start the car.