Ford Crown Victoria 2004 Owner's Manual page 87

Locks and Security
5. Within twenty seconds of removing the second coded key, insert the
new unprogrammed key (new key) into the ignition and turn the ignition
from 3 (OFF) to 4 (ON) (maintain ignition in 4 (ON) for at least one
second). This step will program your new key.
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 dealership to
have the new spare key(s) programmed.
87
2004 Crown Victoria (cro)
Owners Guide (post-2002-fmt)
USA English (fus)