Until recently, eveythign was working fine, but now none of my blinkers nor the brake lights work. Headlights, runnning lights, bed lamp are all ok. I looked at the fuses under the dash but all appeared good. Any suggestions?

 

Most likely your multifunction switch is corroded. The internal contacts are all copper. My right brake light stopped working recently and I traced it to the multifunction switch. Cleaning the patina off the contacts fixed it. You can remove and disassemble it or replace it for around $80.00 from the dealer.

If it's not the switch, then it's the wiring and becomes very complicated.

https://www.f150online.com/forums/sh...ighlight=multi

 

Have you checked the other fuse boxes under the hood? You might be pleasantly surprised. The fuse layout for these is in your manual too. Otherwise, I'd agree on your MFS being a prime suspect.

 

Before replacing that Multi-function switch you might want to check and make sure that the pins in the connectors aren't coming out.. Also if you got a tilt wheel try tilting the wheel to all the way up and all the way down.. If your problem goes away momentarily, then you need a new connector..
Otherwise, I would agree with the possibility of the MF switch itself causing the problem..

Good Luck and Keep me posted!!

FordMasterTech