My daughters Fabia 1.4mpi has developed a brake light fault. The side brake lights work ok but the high level brake light on the back window is acting up. 3 lights on each side light up with lights turned on and go off when lights off but are very dim. When the brakes are pressed the high level brake light works as normal and bright. 

Not sure if it is a fault with brake lights or normal lights and where to start looking. Can’t see where the brake light is getting power from to work with the lights?

@sterling - This might be a bad earth on the tailgate, or one or both rear light clusters..

Hi thanks for reply . I will now start at this point with bad earth . I was going to look at towbar wiring as I noticed the socket cover was slightly open and very wet but a bad earth is worth looking at

thankyou

@sterling Well, in that case that's another suspect for your short, and not one most people would think of without knowing that you have a towbar.