04.5 Ram 2500 5.9CTD Front Driver brake will engage when driving down highway(not touching brake at all). The brake will grind scrape squeal etc until tire is pulled off and i pry piston back open. Caliper piston easily goes back as normal(prying with 14" flathead). Truck drives great till 10more miles and locks itself back up. Took to dealer, they said replace bothe front calipers, pads, and drivers rotor. They said only problem is caliper is locked(what i told them to figure out why in beginning). Any clues before part by part bending over. PS a$$holes want 1049 for just those parts instaled. I will do myself that just bs parts cost me 140 not at discount.

 

Clueless as to how the truck can engage brake without me touching it.

 

That is weird after you installed everything new does it still do it?
if so I would look into changing the master Cyl not to sure never seen or heard that before.. if a caliper is stuck its applying the brakes all the time...
how is the pins that hold the caliper in place? Did you grease those and do they move freely? If those are stuck the piston on the caliper will move freely but the caliper can't release if the pins are seized...
hope that helps Tommy

 

I have an 02 dodge 3/4 4x4 diesel. I have been having the same issues but it is my rear brakes locking up as well the front. Every time i press the brake they seem to get tighter and tighter. to release them I just let off the line from the master cylinder let it bleed off and they become free. there is a little pin right there by the master cylender on an aluminum block seems to be a proportioning valve when my brakes are locked that pin is in the upper position and as i release the pressure it goes to the lower position. in looking for the problem I have replaced both back brakes (cylinders) and one front (of which had one of the pistons broke and when i pryed it out of place it fell out of the housing in about 10 pieces ). As well one of my rear brake shoes had fallen from its guide and wedged itself between the guide and rotor and had been bent severely due to the pistons prying at it. and after replacing all of these parts and discovering all these small issues as well my pickup still has a problem not releasing pressure after the breaks have been applied. any ideas would be greatly appreciated.

 

to the OP, you might check the cap on your power steering reservoir. There was a TSB for the newer trucks that sounds similar to your problem. The cap was allowing too much pressure to build up in the system and holding the brakes on.

jeff.