I started having issues with the brakes on my truck. brake paddle was going all the way to the floor when stoppedbut when driving and hitting the brakes it worked fine. Check the fluid and brake lines calipers and drums did not see any leaks and was not losing fluid. replaced the master cylinder and two portions of brake lines that were bad due to rust. Was able to bleed front brakes after wards but could not get fluid to rear drums. There is some kind of valve on the frame that line goes to for the back then goes to a tee and one line for each drums. Getting fluid to this weird valve but not to the drums. So I took the lever off and was able to bleed the rears but now seems that the rears aren't working again. Anyone with in would be helpful as to what I can do. The fronts work and are grabbing very hard now. Also when this started the brake and abs light came on and had it read. Code 78 foundation brake?