it could be your brake light swich connected to your pedal if your lights are staying in all the time it probably needs replaced or you could have a short to ground in one of your light wirres(probably not) hope this helped you mike
if its a ground problem it could be anywhere. ie: it could be your sterio using the break light ground because the proper ground for it is dirty. that one could be a bit of a big job! lol. I'm not sure. Check for any other electrical problems.