Cummins ISM not reading boost correctly?

[Waterloo]

Replace the Delta P sensor, that moisture you found should not be there, something is wrong. And have you pressure tested your CAC?

Another thing I would do, as I had many weird and wild electrical issues with my ProStar when I first purchased (used) and it was driving me batshit crazy... A mechanic at my local TA pointed out a bad ground when he installed a new alternator, it was all down hill from there...

Start at your battery box... Check your cables for bare wire, exposed bare copper wire, where there should be jacket covering them. Start at the battery box and follow the cabling to their ends, all of the cabling, including the grounds. I found my OEM factory cabling, with exposed copper, in one case there was ten inches of bare copper exposed to the elements! The same with the grounds, I about fell over when I saw what escaped the factory when I really inspected the undercarriage of my ProStar.

I wound up replacing over 100 feet of the stuff, it took me a couple of days and several hundreds of dollars to do this, I have never seen anything like what I found under my truck. After doing this, many of my issues went away, including the funky things my motor would do. It was driving all of my systems crazy, especially at the ECM as the power would spike and drop.

Not saying that is your issue, but it is something I would seriously consider checking out. If my truck came off the line like this, yours could have too, no matter what brand.