The rear brake is not activating the brake light on my 1997 620 RXC. The brake light works fine with the front brake and if I touch the two wires that connect to the rear brake pressure switch the light goes on. So I believe the problem lies in the pressure switch. My question is how pressure switches work? Do they just go bad? The rear brake is long overdue for a fluid change, will a fresh bleed make the switch work again?