brake light

recently , while braking, i've noticed that my emergency brake light comes on. I also noticed that the light comes on while engine braking. The light goes off again as soon as i stop, even with the brakes on. It seems to happen at anything more that just barely tapping the brakes. There also is a little delay between hitting the brakes and the light coming on (my guess is that it's probably the rear brakes because of the proportioning)The e-brake is completely down so i'm not just being a dumbass. I tried resetting the drums by reversing quickly and stopping quickly but that did nothing. what could it possibly be?