I could be really really wrong, but check your owner's manual, the theft light does blink all the time when not running. It blinks real fast if it picks up an uncoded or incorrect key, car running, I think it should be off. :?:
07 GT/CS vert, wife's car, garage queen. sold 11-30-13, going to good home, 7,785 miles.
2013 GT PREM., 500 pckg, needs mufflers...
07 GT/CS, son's car.
1971 Boss 351, mine since 1979.
68 Cougar, my first car, interviewed on Pinks All Out Takes, STL 2008, 10.40's @ 130, 399 Windsor
Son's S/C dragster, SBF 7.92 @ 165 so far......