Brakes

[DaytonDave]

Brake pedal went almost to floor. Still stops the truck, won't allow me to shift out of drive. Now truck won't start. 2014 2500 big Hemi auto.

 

[tron67j]

Could be a bad caliper, or even master cylinder. Have you checked fluid level? Did you do brakes in the recent past; could be air or even moisture in line. Maybe have a shop check the components.

 

[Daw14]

Have you looked for dripping fluid or puddlEs where you park. You may have a leak , but they usually show themselves.
Inspect the rubber hoses at all four corners and on the axle.

If nothing shows it might be internal to the master cylinder.