I don't know if this is the case with yours, but it may be:
The brake lights in my truck are also my rear turn signals. So if I put my left turn signal on, that's my left brake light. The same goes for the right. So if you put your left or right turn signal on (don't forget to put the key to accessory), do the lights flash?
Try the 4-way/hazzard lights for the same reason.
I had a problem with my turn signals (front&back), parking lights,
4-way/hazzard, and stop lights all were blowing their fuses -- but not the bulbs. It ended up being the trailer light harness was corroded and shorted out.Just some odd ideas -- it's a newer truck so I would be suprised if it was corrosion -- unless you were playing with something ;)
-Joe