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IIRC you do not need to dump the tires down to emergency pressure when using the run-flat button. You can hit run-flat and Hwy just the same, and it should keep the CTIS from timing out as quickly. Stellaevil is the subject matter expert on this and could correct me if I’m wrong.

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 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...

Do you have a tire, or two that goes down over time? Ditch the rotten dust cover on the QR valve. Inflate all the tires to the same pressure, then see if the QR valve still exhausts while attempting to fill the tires. If it does, pull it off and check for debris in the rubber flap, or the flap...

My bets on a leak. Spray a thick mix of soap water on the wheel valves, especially the rears where they connect onto the adapters. Did you try hitting the runflat button to see if it will continue to try inflating?

Ok, now I'm with you. Wrong truck...

Are you working on the front axle or one of the rears? Also what part of Indiana are you from?

Can you post up a picture of the banjo bolt you are talking about?

I'll bet therooster2001 and 74m35a2 would love to hear your thoughts on the "M939 CTIS reprogram, Anybody done it?" thread!

I wonder if the transducer could be the problem, especially with 70deuce? Tinstar, the only thing I see is, all the axles feed from just one line and Tee out to the axles. So if just the front axle was airing down, you at least had a problem with a front wheel valve or dump valve.

If you have shop air to charge it with, it's a lot easier to listen for leaks without the truck running. Master switch must be on as well as start switch in the run position for the CTIS to cycle. Also hit the run-flat button to keep it trying longer and more often.