That light can illuminate 3 ways. #1--- Parking brake switch faulty (doubtful). #2---- EBD source (Electronic Brake Distribution). You would *not want* that to be the problem. #3--- Your master brake cylinder has an internal *low level* sensor in the fluid reservoir. It could be faulty, or hopefully you need to add more brake fluid to it. That may correct that sensor from seeing or sensing a low fluid level in that reservoir (even if it doesn't appear to be low).