Cummins ISM not reading boost correctly?

[Waterloo]

One other thing, check the power wire that runs from the battery box to the ECM. There is an inline fuse, I would replace that, as they do go bad over time, but will not actually blow. There is also on some a resistor or something like that, it escapes me right now... But it will be inline too, those sometimes go bad. This is a simple thing to check along with your cabling.