Sounds like the brake light switch.There's a switch that turns on your brake lights. From your brake pedal, follow it up. (You may need to remove a panel or two to see up).Somewhere between the pedal and where it exits the firewall, there's a switch. It's highly likely that this switch is broken or got out of adjustment.It should look like this:http://www.autozone.com/R,NONAPP8096...Detail.htmWhen you set on the brake pedal, the switch should pop out and close the electrical circuit (turning on the brake lights), when you release the brake pedal, it will push the switch in and break the circuit turning off the brake pedal.