Brake lights and Flashers

1999 GMC Suburban 190,000: The brake lights and flashers do not work. When I push in the flasher button the turn signals do work either. When I push in the flashers and hold the button down the arrows flash for a couple of times and then quit, but they never work it I push the button and not hold it. I do have running lights. I have checked the bulbs and I don't see anything wrong with the fuses. A short somewhere? Any ideas? Thanks.