1997 gmc sierra extended cab - turn on the right turn signal and all of the lights go on but do not flash on and off and get a single buzz from the flasher unit. turn on the left turn signal and all works well and flashes. this is with the truck running. turn the truck off and turn the key forward and both the left and right turnsignals function properly. any suggestions?

i replaced the combination flasher on the lower left side by the drivers left foot (about a 1 inch square black box with four male prongs) and everything worked the same. is there another flasher somewhere else? i also checked and even though they don't flash all of the bulbs turn on when the signal is on and the engine is running. if the key is forward but the vehicle is not running they will flash. i replaced the combination flasher on the lower left side by the drivers left foot (about a 1 inch square black box with four male prongs) and everything worked the same. is there another flasher somewhere else? i also checked and even though they don't flash all of the bulbs turn on when the signal is on and the engine is running. if the key is forward but the vehicle is not running they will flash.