does it stay on even after the car is completely shut off, if it is then there is a small switch behind the brake pedal that triggers the brake lights when you step on the brakes. that switch might have broken off resulting in your brake lights staying on all the time (kinda like you're stepping on ur brakes all the time cus the switch isnt there to depress the trigger). same thing happen to my brother in laws 95 lx and we replaced the little rubber switch/little thing that sticks out a little bit behind the brake pedal and the brake lights started functioning properly. you might have to search for it a bit by following the rod up kinda under the dash following the main pedal(part u step on)is bolted on to.