I have attached the test procedure from the shop manual.

 

Awesome thank you for that!

And great news I solved my issue, though it pissed me off quite a bit. Took the truck for a drive and just slammed on the brakes and immediately fixed the problem! The valve must have been stuck on the abs or something

 

Reminds me of this.

 

Kind of sounds like a possible bad hydro booster. Will the brakes pump up and hold w/ engine off? The test for booster is, engine off pump brakes until hard and hold. Then start truck, pedal should fade slightly during start up then actually push back and hold once running. If it no push back then booster is likely failed.

 

I believe it was the dump valve in the Hydraulic side of the abs. Been there done that.

 

Sort of unrelated, but I figured this was a good thread to ask on. I think I may have a problem with my brake pedal as well. The other day, due to my oversized tires with the incorrect rims that have too much offset inwards, my tire rubbed a hole through one of my brake lines and I had to run a stop sign at a usually busy intersection but anyway, I replaced the brake hose, and bled the brakes and here is where the issue comes in. Now that I think of it the pedal is always been this way but, even with the hose busted and no brakes the pedal only goes down about an inch and a half from where it rests and almost feels like it hits a pedal stop or something. I thought the pedal would go all the way to the floor with a busted brake hose but, it's almost like it has a pedal stop on it and it just won't go below that point and it made it rather hard to bleed the brakes because the pedal only went down just a smidge from resting point instead of really pumping the brakes up so, even with no brake hose the pedal did not feel all that squishy because I hit a stop. Not sure what's up with that. Ideas? I replaced the booster not too long ago with a good used unit from Eric that had low mileage.

 

Yeah, the brake pedal needs to be able to go to the floor if the hydraulic part is not pushing back, but the other half of the dual master cylinder won't let that happen because you're hitting the fail safe that is built into that system. If you open both a front and a rear bleeder at the same time, the pedal should be able to be pushed all the way to the floor. If not, there's a mechanical obstruction preventing that and for your safety's sake, that needs to be addressed.

 

If the new master cylinder was properly bench bled and you managed to get the air out with your odd way of bleeding the cylinders and calipers starting with right rear cylinder, left rear cylinder front right caliper and ending with front left caliper purged of air then it seems likely that either
1.your brake booster could failing or has a small vacume leak. Inspect the vacume line from the plenum to the booster and the 90 degree connector rubber grommet on the booster it fits into.
2 One of the caliper's rubber line is expanding under pressure or the rear rubber line that supplies the rear cylinders fluid.
it all of those turn out to be good go around it beating it with a plastic baseball bat. It won't fix it but you'll probably feel alot better considering all the time and money it's costing you.

 

@Jacob Holtzclaw The brake boosters in the diesel trucks are Hydroboost (i.e. no vacuum) but your point is well taken.