Ok, I’ve been trying to research this, but I only find answers to the blue line, plus a couple of mechanics told me what to try. Still happening.
When I disconnect the tractors red glad hand from the trailer, air flows out of the TRAILERS red glad hand. It empties out all my air from the 5 tanks I have. I have 4 drop steering axles and 2 fixed axles. I don’t think the 3 tanks to the smaller drop axles are the problem. The 4th tank goes to the super single drop steer and the 5th goes to the 2 fixed axles. When hooked up, the truck and trailer both roll and brake fine.
Any help is greatly appreciated.