It's probably not broken-very rare.
First, pull the driver's seat all the way back so you can lay on your back to see up the length of your brake pedal. (under dash) If you're smart, you'll take your flashlight with you FIRST time.
The only thing you'll see pushing against the pedal will be the switch. Push the pedal and observe the switch while doing it. It should move in/out with each pedal push. If it doesn't move as fast as the pedal, apply spray lube or or in a pinch, vaseline- to it, then work it by hand repeatedly and briskly. ( I wish I could word that differently....)
If this fails, it probably needs replaced.