Simply turn on the ignition but do not attempt to start the engine. If the light bulb is good you will see the Check Engine light illuminate and stay on. If you do not see the Check Engine light, the bulb is defective or has been removed.
To change the check engine light bulb on a 1996 Crown Victoria you need to remove the molding from around the instrument panel. Next, remove the headlight knob and shafts. Locate the light bulb and turn counterclockwise to remove. Reverse directions to replace with a new bulb.