theft light

i have a 1996 mercury sable wagon. we had to change the battery in it today and now everytime i try to start the car the theft light comes on and the car shuts right back off. now i have heard that when you disconnect the battery that there is something that you have to do to reset the theft. i heard one possible solution was to lock the car with the key on the drivers side unlock it and then start it. i tried this and it didn't work. can anybody tell me if i am supposed to wait before i try to start the car or start it right away or if there is any other possible solution. i would be very greatful for any help anybody can give me.

I would like an answer to this same question I did some work on the steering column now the car wont stay started and the theft light goes on. when i spoke to a dealer they said I needed to bring it to them so they could scan in the key code (there is a chip in the Key). When i do programing for equipment I alway try to leave a back door fix for quick repair. if anyone knows a quick fix for this problem it would be appreciated.

Go to http:www.obd-codes.com/howto/patskey.php
it didn't work for me but might be worth a try.