is it all 4 corners That the signals dont work? or just the fronts? If its all 4.. it sounds like the Gem Module located in dash behind the radio... Or if it works when hit a bump or somthing, It could be the flasher its self.

 

The only thing that doesn't work is the front drivers side turn signal/hazard and the the one on the dash that blinks when you have that same turn signal on. That bulb works when the parking lights are on even.

 

sounds like a wiring problem somewhere......