1 If the brake warning light does not go out after you add fluid, check the cylinder tank again. 2  If the fluid level is very low, you have a major leak or multiple leaks.3  You should call for help and get the car towed to a mechanic.arnings. 1  If the brake warning light does not go out after you add fluid, check the cylinder tank again. 2  If the fluid level is very low, you have a major leak or multiple leaks.