Brake and blinker lights are not working
How about the cruise control? It could be the brake light switch.
There could be a short in the trailer lights plug or wiring for it.
did you check your fuses and bulbs to see if they were just burnt out
Looking for a Used F-450 Super Duty in your area?
CarGurus has 2,598 nationwide F-450 Super Duty listings starting at $7,500.
Search Ford F-450 Super Duty Questions
Ford F-450 Super Duty Experts