There may be a short in the relay to your tail lights. When you hit your brakeklights a certain amount of power is pushed out by your relay or brakelight switch to illuminate. If Your lights are on and it is on all the time, there is a problem with the voltage dispursal. This could be a short, brakelight switch or relay. Try replacing relay 1st, then brakelight switch then you will have to take it to auto electrican to see if he can find short.

PS, Do both brakelights work? if not change bulb, that could be voltage issue also.

This could the problem with the brake switch get it checked it will fix the issue.................