I would bleed the brakes again. Use a person to work the pedal. Air in the abs module can be PIA to get out. Just for your satisfaction, and to make sure there are no leaks. Do what Truedogman said.

 

After driving the truck for a day, the pedal seems to have "hardened" up. Not sure why there would be a delayed effect after the bleed, but all seems well now.

 

I know this is an old thread...so this is for future thread-seekers.

A quick way to check the ABS pump is to put the pedal to the floor and then start the truck to engage the solenoids. I'v had it help push the air out and tighten up the pedal.

 

Coming back to this old thread after many months for an update-the brake bleed didn't help. It seemed like the pedal hardened up but I think that was just wishful thinking because it felt mushy again right away. I tried both the Power Bleeder method and the pedal pump method again and neither one helped at all.

Ended up taking the truck to a different dealer.

They thought the new Master Cylinder was leaking, replaced it. Bled the system. Still Mushy. (By the way, this dealer did NOT claim the bleed was "a maintenance item" and try to stick me for the cost)

Found the Brake Booster Push Rod was bad-Replaced the Brake Booster. Still Mushy.

Replaced both front calipers. Nope, Still Mushy.

Replaced the ABS Hydraulic Control Unit and Module and that took care of the problem. My Brake Pedal is finally firm again.

It took some time-they had my truck for 2 1/2 weeks trying to figure it out, having parts shipped in etc, but they did get it done.

Disappointing as far as the first dealership that they just replaced the Master Cylinder and shlepped the truck out the door without making sure the problem was actually fixed. Plus wanting to stick me for about $120 to bleed the system which it would seem should be included as part of replacing the MC. Even if I'd coughed up the $120 it would not have fixed the problem so I'm glad I said no to that.

Very thankful right now that I have the Max Care Lifetime Service Contract. It sounds like they replaced most of the Brake system short of the brake lines, pads & rotors and I would guess that would have been a pretty big bill. Only had to pay $100 deductible. Plus I got a brand new Durango as a loaner.

 

Glad you got this sorted out, and thanks for the update on what the problem turned out to be. It could be good for future reference for someone else.