Dude, you're going to have to give more detail about what you're talking about. . . . . So the brake lights come on when you push the brake pedal. . . . but they don't flash? Why would brake lights flash?
^^^ do that and check ur bulbs i just had this happen and my bulbs for the brighter flash wire in the bulb was out. there are 2 wires in the bulb the top on is ur running ones for night then the lower one is ur braks when u hit ur pedal.
mine did that exact thing a while back. turned out to be a loose wire coming from the brake sensor switch thing to the multiswitch stalk thing. just check that out. check to see if the one behind the cab is working