I blew a brake line from the box under the master cylinder and goes to a box behind the transmission. So it sat overnight and now I have now pressure at all. They don't even pump up enough to bleed them. I'm confused and could use a little help.

 

When you pump the brake pedal, does the fluid in the master cylinder go down? You lost a lot of fluid and may have to refill it all before the pedal gets hard. You may also have to bench bleed the master cylinder if the fluid does not go down when you pump the pedal.

 

Welcome to the forum. Moving to the Silverado section of the form where you will get more views.