I have a 2004 F-150, and have had nothing but problems with this thing. The latest issue is my turn signals. They have been working fine since I got the truck until today when I realized I had no turn signals and no hazards. I checked the fuse and it was blown. I replaced the fuse, and it blew again. I put in 30 amp fuse instead of the 20 amp, and tried again to see if it would hold. The left turn signal works fine, but the hazards wont work, and when I try the right, I hear the clicking, but I get no turn signal, and Im getting a massive draw on power. I am not exactly sure where to go from here. Only thing I can think of is that it may be a bad MFS? The only thing I have recently done as far as electrical is replace the power window switch on the front left door, and had a new right front turn lamp replaced.
Added note, The right front and rear lamps both work, they just wont blink.

 

I don't know squat about your problem specifically haha. But, putting in a larger fuse generally isn't a good idea. And if a motor is going out or bad, that's usually when it draws large amperage and blows fuses or wears relays and switches out. I have no idea how our blinkers operate or what controls them (don't know if they have a motor), but I'm highly inclined to think something is fixing to call it quits in your electrical system and that's why it's drawing a lot of amperage. Hopefully someone else knows more than I do and can shed a little light on this situation. Otherwise, I'd say to have a professional diagnose it. I hate paying people to look at my truck, but electrical stuff can be extremely tricky when you don't know what to look for

 

It sounds like a chaffed wire. First, take all the bulbs out. Then replace the fuse with a 20 amp fuse. Does it still blow? If not, then I'd do a voltage check on all signals with a meter, one at a time. Hazards will work... or just left and then right.

Take it one step at a time.