The switch or the relay, check the cheapest, or simplest thing first, which could be the relay, but the symptom points more to the switch.
I would replace the headlight switch as Ford has had their share of these problems.
faulty wiring or you are accidentally hitting the switch and not realizing it
blow fuse, bad motor, bad switch or wiring
bad headlight switch.
depending on the vehicle, of course, most likely cause would be the combination switch
yes it will also cause them to blink off & on and
it's your headlight switch
Theres a switch 2 buttons to the left of the defroster switch. That switch is to raise and lower you head lights without turning them on so you can change the headlights. The switch could have a short in it causing it to act like that.
bad light switch.
Headlights need to be on for starters. Blown bulb, relay, or switch.
Is your headlight switch and blinker switch the same? If so, this is called the combination switch. Sounds like it is bad and needs to be replaced. Not uncommon for these to break.
It could be a fuse, a relay the switch