On certain vehicles, the body control module (BCM) may not have been manufactured properly. As a result, the trailer taillights may not work when towing a trailer.
Safety Risk
Trailer taillights that don't work could make the vehicle less visible to others and increase the risk of a crash.
Corrective Actions
Ford will notify owners by mail and advise you to take your vehicle to a dealership to inspect and, if necessary, replace the BCM.