When I put the brakes on the headlights dim for a second and the tac & speedometer go to the bottom and then go back up when I hit the gas, The engine doesn't cut off.
You either have a weak battery or weak alternator, other things could be bad light, a short or bad relay or fuse. Put your foot on the gas till 3000rpms to provide more charge while in park then push the brake peddle. IF the lights still dim you have a short or bad fuse or relay. If the power stays constant you most likely have a bad battery or alternator. You can have this tested at a VW specialist shop. i would susggest it soon since a short could fry the computer components in your car easy