Changed battery and now anti-theft wont let car start.Any help would be a great help.

 

When the vehicle refuses to start, leave the key on 10 minutes, the theft litemay go out. Turn the key off for 10 seconds. Try to start, if it starts and stalls or refuses to start, do the procedure again. Don't turn the key off after cranking, leave it on, do the 10 minute and 10 second procedure. You may have to trythis three times.

This procedure will work in some situations. I can't say it will work all the time.