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It can take some time to fill up all 6 tires at once, depending on the CTIS starting pressure and at what rpm and duration the engine has run at. You can get some idea by watching the stock gauges to see how fast your trucks air pressure is recovering while in fill up mode. The CTIS system will open up the trucks air supply to the tires after the trucks supply hits around 120 then it will continue filling unless or until the trucks air pressure drops below 90 psi. Then it will stop and wait for the trucks air supply to recover back up to 120 psi and repeat this cycle until the CTIS either reaches 70 PSI or if there is a leak, until the leak gets too bad, then it will shut down itself and do the "5 blinkys". So as you can you see, if you have no leaks in the CTIS but leaks in the rest of the system it will still cause a slow fill up. Leaks in the CTIS just compound the problem, and visa versa. I ended up putting an air pressure gauge on the outgoing line from PCU. That way when the system is in fill up mode I can visually see what pressure it has currently reached. BY watching this gauge and the other two it gives you a visual look into what the CTIS system is doing. Its not necessary but it is helpful.
