this happened to me on my 98 Honda accord and it was because my brake lights and sinal lights were not working properlyMost likely, the brake light switch is stuck.
Have you checked your brake fluid level? You could be dangerously low.
If you mean that your exterior brake lights stay on even when you aren't pressing on the brake pedal, you most likely have a bad brake light switch.
If you follow your brake pedal arm up under the dash, you should see a switch that comes in contact with the arm. It might have been knocked out of position and all you need to do is put it back. If it is in its correct position, it is probably bad and will need to be replaced.
It works like this...when you press on the brake pedal, the arm moves away from the switch, thus turning on your brake lights. When you release your foot from the brake pedal, it contacts the switch and your brake lights turn off.
Check the switch on the brake pedal
brake light switch would be most common cause
Possible ground issue at the taillights.
BAD BRAKE LIGHT SWITCH AT TOP OF BRAKE PEDAL
More than likely it is the brake light switch that is attached to the brake pedal.
The BOO (Brake On/Off) Switch may need to be replaced. If it is bad, it would cause the brake lights to NOT illuminate when the brake pedal is applied.
Check your brake light switch at hte brake pedal.
brake switch located on the top of the brake pedal
The most likely cause is a bad brake light switch (if none of the brake lights illuminate) but if its only one of the brake lights, try changing the bulb. Even if they still work as running or turn lights because they have a double filament and may still work partially, but not as brake lights.
Check the switch adjustment on the brake pedal arm.
Blown fuse, bulb, or bad brake light switch.