There is a little plastic plug that fits into an angled thingy on the brake pedal. This has probably broken apart and now there is nothing for the switch to actuate against. I have fixed both of my Monteros with a nail or screw epoxied in place in the hole that is left over. This will give the button something to press against and turn the lights off. I bet its not the switch.
John

SOLD!!: 91 LS 95 SR Rear LSD front 95 LS front brakes Dons Bumper 10k Gorilla/Promark winch Safari Snorkel Dual bouncy 31's

1991 Chevy Suburban 33's. All other stock.