You may have a bad hub seal allowing a little gear oil into the CTIS. That could likely swell the diaphragm in the wheel valve as well as the QR valve flap and cause problems.I finally got some time during my furlough this week to look into my 5 flashing light problem. Once the truck hits 120psi, the system does a check and goes right into the 5 lights. I checked the tires and the front was at 50, the middle was at 50 but the rear was at 40, both sides. I aired the back up to 50 and tried again with the same result. I checked the axle vents and they are not leaking. The two back tires both had very small leaks at the bottom of the wheel valve where the hose goes into it. I took the wheel valve off, cleaned everything up, put some thread tape on and re-assembled it. The leak is fixed. however, I noticed there was a little oil in one of the wheel valves. I'm guessing that shouldn't be there?
The CTIS worked perfectly since I got the truck up until January.
I also found on one of my tanks, the shutoff valve was leaking a good air. I haven't looked yet but I'm assuming those aren't re-buildable?
I should have some used wheel valves around, maybe even a new one or two. Let me know if you need them to try.
I think most people just go to full port ball valves when the tank shutoffs go bad.