The procedure for replacing a fog light varies from vehicle to vehicle. On the Ford Fusion, you'll have to access the rear part of the fog light (instead of pulling the assembly from the front) to change the bulb. Fortunately, you do not need to lift and support the vehicle. If your fog light bulbs are burnt out, replace them as soon as possible.
Turn the fog light switch to "Off" and shut your engine off for safety.
Position your creeper in front of your Fusion, between the two fog lights. If you don't have a creeper, lay a towel on the ground to keep from getting dirty.
Locate and remove the four screws securing the front part of the lower splash guard. Pull the guard back to access the fog light sockets.
Rotate the fog light socket counterclockwise; pull it away from the lens. Pull the bad bulb from the socket.
Attach the new bulb to the fog light socket, while holding the base of the bulb (not the glass part). Reinsert the socket into the rear of the lens. Rotate it clockwise to lock it.
Repeat the procedure for the other fog light, if needed.
Reposition the lower splash guard. Tighten the screws to finish.
Turn your fog lights on to determine which one is burnt out. Don't replace the bulb if it's not out. Bulbs are normally sold in pairs; however, you can save the other bulb in case the other fog light burns out.
Working underneath your vehicle with the engine running is dangerous, and can result in bodily injury. The oil and dirt from your bare hands can cause the bulb to dull or prematurely fail. Hold the bulb by its base to avoid this.