Ford 1997 Crown Victoria Manual page 211

Working with the engine off:
1. Set the parking brake fully and make sure
that the gearshift is securely latched in P
(Park).
2. Remove the key from the ignition after you
turn the engine off.
3. Block the wheels. This will prevent your
vehicle from moving unexpectedly.
Working with the engine on:
1. Set the parking brake fully and make sure
that the gearshift is securely latched in P
(Park).
2. Block the wheels. This will prevent your
vehicle from moving unexpectedly.
Do not start your engine with the air
cleaner removed and do not remove it
while the engine is running.
RWARNING
211