Brake Pedal to the Floor? Don't Gamble, Get It Fixed

The pedal should not "go to the floor" at any time. There should come a point in the pedal travel where it no longer moves down. There was a previous thread that indicated the rubber brake lines are a probable source of weak brakes. ... https://www.amazon.com/dp/B0130X8XIE? Yes, the pedal should drop when the engine is started and vacuum is supplied to the booster, but the pedal should not go all the way to the floor! The brake peddle is firm and at the top when the engine is off but sinks to the floor when you start the engine. The Ford dealer said it could be the master cylinder or an ABS module. My question is, can you trouble shoot the Abs module and Master cylinder and not just ... Brake pedal to the floor is a classic symptom of master cylinder failure. The fluid simply bypasses the seals on the piston in the master cylinder. I'm facing the brake pedal that works but after fully stopping the vehicle and still holding the brake pedal, it will sink. No dash emojis (warning lights) no ... Pedal going to the floor is a usual indication of leak or air in the system. But If you have a leaking brake booster, vacuum lines to it and if I am correct ... Most common causes are leaking brake line or brake cylinder. Have someone press the brakes while you look under the truck for leaks. No leaks? If the brake pedal is going to the floor do you have air trapped in the system. You will need to bleed the brake system to get all of the air ...