I put in a new bulb and suprise...the brake light is constantly on. Is the light just supposed to tell you the parking brake is on or does it indicate a problem in the brake system like modern lights. If so, what problems would trigger the light. The car has front disks. The rear wheel cylinders are leaky (going to replace em' this weekend). I do keep the master cylinder full though. Would this cause the light to come on? Or is it just a broken parking brake light.