Switches on the steering wheel go out too. Press and hold off button while turning the key on. The cruise control light should flash. Then press on, resume,coast, set/accel. With each button press the light should flash indication that switch works on the last button if the light doesn't flash and no other flashes happen that switch is bad. If it doesn't light and more flashes come out I means there is a fault. 2 flashes indicates brake pedal switch fault, 3 flashes indicates deactivation switch fault which is what others are talking about and 4 flashes is a problem with vehicle speed input. If unsure just google ford cruise control self test. It's pretty much word for word out of the workshop manual.