307edition
Newbie
Okay this is a long one. I’ve got a 98 k1500 4wd that locked up on me on my way home from work one night a couple of months ago. I could pump up the brakes but they would not release. The brakes have always been sketchy on that truck and I was planing on revamping the system soon anyways so it wasn’t a huge deal. I started by replacing the brake booster, master cylinder, rubber lines and the front calipers. Here I ran into what I thought was just a bleeding issue as the pedal had no bottom to it. The brakes would work, sort of, but never really anything more than just being able to hold it when I put it in gear. I ended up running nearly 4 gallons of fluid through it between traditional bleeding, scanner on the abs, and pressure bleeding. My locking up issue wasn’t resolved so I replaced the whole abs module with a refurbished one and it fixed that but I still have no pedal. I took it to a shop and they believed it was the rear drums so those are also all brand new now. They had it for over a month and it stumped every mechanic there. I got it back and tried some isolation tests with plugs. I have hard pedal at the master cylinder. I couldn’t totally isolate the abs since the front right is a different fitting of course. With just the front right I have brake pedal like it was originally, kinda squishy but still had a bottom. As soon as I add either the other front or the rear brake lines the pedal disappears. My current theory is that the valve body isn’t functioning properly but any insights would be greatly appreciated!