I have a 07 Night Rod and while I was at work the brake pedal went from fine to barely existent. I could easily push it to the floor and it barely worked. There are no leaks, no puddles, everything is dry.
So far I have bled the lines and rebuilt (right phrase?) the master cylinder with a rebuild kit (42883-06A). Everything was fine for an afternoon but the pedal is getting soft again.
While searching I read that the brake light switch (which IS out and needs to be replaced) could cause this but it was a passing comment and that was the only time I heard that the switch could be the problem.
Before I replace the switch or at this point, all of the lines, how can I troubleshoot what the problem is?