Ford Crown Victoria 2011 Owner's Manual page 88

Locks and Security
6. To program additional new unprogrammed key(s), wait at least
20 seconds and repeat this procedure from Step 1.
If successful, the new coded key(s) will start the vehicle's engine and the
theft indicator will illuminate for three seconds and then go out.
If not successful, the new coded key(s) will not start the vehicle's engine
and the theft indicator will flash on and off. You may repeat Steps 1
through 6. If failure repeats, bring your vehicle to your authorized dealer
to have the new spare key(s) programmed.
88
2011 Crown Victoria (cro)
Owners Guide, 3rd Printing
USA (fus)