The trailer air supply valve will not stay engaged by itself. The trailer does charge if I hold it in but then the yellow valve pops out as well. Weird. No major leaks. Lots of air pressure. Tried several trailers. Same story. Ideas?
Then, you’ve got something leaking somewhere. Either a brake can leaking back on the service side, through a relay valve, or the inturnals of the tractor protection valve is back feeding. Or, someone hooked some **** up wrong on your valve to mess with you.