Good point
I am surprised that the PCM doesn't throw a code when the dump valve is malfunctioning. It's kind of a dangerous situation!

 

Update: I am picking up a new dump valve from Napa today. The online one was cheaper, but a week away. Napa in Albuquerque only had one, and it was at the main warehouse downtown!
I guess I'll try to get that booger in this weekend.....

 

Crap! It looks like this new valve has different mounting stud pattern!
I don't know yet if everything else is the same. I'm going to look it over really well in the morning...

 

Before changing any more parts, I'd be bleeding and re-bleeding the system. You're describing air in the system. One little bubble can cause all kinds of problems.

 

The new ABS hydraulic dump valve just had an extra stud, but it's identical to the one I pulled out. The main brakeline was fused to the nut, so of course it twisted off. I had to drill out the flare nut, get another piece of line and a union and make a splice. Sure glad I have a tubling bender! Anyway, got it all on last night, and with the exception of all the air in the lines now it's working better. I am going to have the brakes power bled today. I hate bleeding brakes with a passion! Thanks to Wanna for the call on the valve.
Mark

 

Felt guilty, so my wife and I bled the brakes. I bled about a quart of fluid through the thing and it does feel much better, but I'm still getting pedal leakdown. It's a lot slower and stops sooner, but it is bleeding down some. I'm starting to think there is a taper in the Master Cylinder bore. I should have gone with a new one!

 

Master Cylinder worked out it's issues overnight, but front brakes started grinding on drivers side. I guess driving without the rear brakes because of the dump valve malfunction fried the fronts.
The inside of the drivers rotor had gone metal to metal, and was wounded, so I put one of my used sets on the truck to smooth out the rotors a bit before I put the new carbon metalic jobs on there. I also adjusted the rears (they were way out) and now the brakes are solid.
I don't know how to tell how much brake lining is on the rears without pulling out the axles.
I wish somebody would design front and rear brake rotors and drums that can come off independently of the hubs. I really hate this setup