bad master cylinder
Hissing from the brake pedals being push indicates that there is air in the brake system. It also indicates that the brake pads may be wore down and are not able to grab to stop the car.
it is hissing because there is a vacume leak in the brake booster it will require a new brake booster
Faulty Vacuum Brake Booster.
brake switch located on the top of the brake pedal
Brake pedal switch bent or loose on its bracket under the pedal? Carpet pushed under the pedal pressing against the switch?
Check the brake light switch on the brake pedal
Your brake booster is malfunctioning
When your foot puts pressure on the brake pedal there is a switch that relays the brake pedal being pushed to the lights which makes them turn on.
bad brake light switch
Adjust or replace the stoplight switch at the upper end of the brake pedal under dash area
Follow the brake pedal up behind the dash. The pedal arm ususally operates a button that turns on the lights when the pedal is pushed. The button could be stuck.
Should be located at the upper end of brake pedal