you might have to change the bulbs. open the light housing in the trunk. there is one clip. just pull on it jently, because most of the light housings on Supra's are busted/cracked or soon to be. look at the bulb that has 2 filaments, one is for light ON when you turn the headlights ON, and the other id for when you Brake. check if the first filament is cut.
that might be the problem. if that that doesnt work, then start digging the fuses.
GOOD LUCK