Why do my front, rear and dash signals come on when I press the brake

I just bought a 1997 k2500 cheyenne as a fixer upper. Most of the electrical works but the turn signals don't work. When I press the brake the signal lights all come on including the dash. I cannot find a proper wiring diagram for this truck. The brake relay clicks but sends power to front rear and dash turn signal bulbs. Any ideas what to check