ford focus brake light help

[1991fordranger]

Okay on my girlfriends 01 ford focus se the brake light comes on every now and then and will stay on but if you tap the brake 3 times it goes off.. its not the parking brake so what could it be?

 

[Explorin94]

Wwhich light(s) the dash or tails? If it is the dash light check the brakefluid, if it is low check the brakes before you decide to fill the resevoir. If it is that tail lights you may have a bad brake switch.