Thanks, Do you know where abouts in the footwell?

It's strange, when I press the brake just enough for rear lights to come on the headlights dash and brake lights flicker/dim really quickly for about 2-3 seconds like it's surging/draining power from somewhere.

And if I press the brake, let it flicker, then let go and quickly press brake peddle again it doesn't do it, it's like it has to build up some sort of charge?