Parking Brake Light

I have a '91 2X4 in which the parking brake light will "come on" when I accelerate quickly or am going up a steep incline. I've checked all the wires and connections but have not yet replaced the switch with the depression button at the base of the parking brake rod. Is it possible that something in there is lose and is shifting around? I found out by accident that if I slam on the brakes hard the light will go out! Thanks in advance. H-S-F