Changed the brakes and the Master cylinder the pedal still goes to the floor

The brake shop that replaced the master cly. 2 times said they blocked off the abs system somehow and determined that there was nothing wrong in the brakes that the problem was in the abs system. It doies act just like a master cly with an interna leak but with the abs system being all vac. I was not sure that it could act the same.

Thanks for the guides it was the master that was out

I have the truck listed above 1500 with rear wheel ABS only. The infamous brake line that goes from the front junction block to the rear hose/junction block blew out. I replaced the line and went to bleed the line by bleeding it out through both rear bleeders. Starting at the right rear. I had a friend pump the brakes and hold pedal while I open the bleeder. After many repeats of this process no fluid came out. I then started the truck and did same process and after 1 time fluid came out. I bled all the air out so I moved to the left rear. Bleeder screw was seized and I wound up snapping it off so I replaced the left rear wheel cylinder. Repeated bleeding process and no fluid. Started truck and repeated process and fluid came out. Bled out all the air from both rears and pedal is still almost to the floor. When you start the truck no lights are on but after pumping brakes the brake and abs lights come on. I have read online about the proportioning valve and how it controls the rear brakes to prevent skidding and about using a scan tool to activate the valve etc. Since the line I replaced was after the prop valve and rwal unit I don't see why i'd need to worry about bleeding them? I read that if the valve is off center in the prop valve it'll kick the brake and abs lights. Master cylinder was never ran dry during any of the process. Any suggestions? Thank you

If you pump the pedal it will build up but not much at all very minimum. If you hold the pedal it doesn't fade but it's just very low. Solid streams of fluid come out of the rear so I am wondering if there is something wrong with the rwal valve or hcu. But not sure how to test them.

Sorry for delay in response. It wound up being the master cylinder sucking air. So I replaced it and fixed the issue. Thank you to you all.

Brakes problem
2001 Dodge Ram Two Wheel Drive Automatic 60k miles

I had a brake inspection done, due to the brake pedal sinking to the floor. The results of that said front brake pads are low, and rear shoes low but neither in an emergecy situation. I was told and also as the report says master cylider needs replacing, due to floor going to floor. That was my hunch it was before going in for check. The brake pedal to floor started 2-3 days ago as I got in and noticed the pedal went right to the floor upon first brake depress.
I replaced the master cylinder, bench bleed it first and installed the new one in. Needless to say the brake pedal still goes to the floor and the ABS and BRAKE lights are stiill illuminated to. The pedal feels like it sinks to the floor at the rate as before, so I am thinking a brake bleed at the wheels would not make a huge difference at this point. Could it be with the brake booster? Thanks to all!

Thanks for the reply MJ. I got it figured out. With some more investigation it proved to be a defective master cylinder right out of the box. Exchanged it out at the auto parts store, bench bleed the new master then bleed at all four wheels. Brakes work like new again! I like it when things work as they should!
Thanks

I was driving and my front right caliper busted the seals and brake fluid leaked out of it and my whole front brake system failed and I had no brake pedal pressure at all and I was just driving with my back brakes only. I replaced both calipers, pads, rotors and bled the fronts only. Now when the engine is not running when I pump the brake pedal there is some pressure but it slowly sinks to the floor and comes back up slow. When the truck is running there is absolutely no pressure in the pedal and it goes straight to the floor. But the back brakes are still working so could it be a bad master cylinder or could there still be air in the lines or something else? Now the whole time the abs and brake lights stay lit on the dash as soon as I touch the pedal when the motor is running

First I will start with what I know about my situation. There are no leeks, no air in the system. I have bled a gallon of fluid through it and no bubbles. I have replaced the master cylinder and the booster. I have tested three different ABS modules. The brake light and ABS light are on. It will build little pressure while the truck is off but when I start the truck I lose everything. PS: I bled the lines while it was running and while it was off. I am scratching my head, please help.

Front brake line blew all fluid came out replaict line filled fluid and blead have no pedal does master have to also and how?