Its a Volvo Problem

[RyanC]

I think this is getting over thought.... the hose that's leaking is stopping your truck from building any air. Follow the hose that's leaking to the next valve or component it plugs in to. Disconnect all lines from it to find which one air is coming from. Do the tests and see if air is supposed to flow that component under your conditions. If it is supposed to flow then follow to the next component and repeat.

Opening loom sucks and in winding the birds nest of bullshit is worse.... but sometimes you gotta go caveman style and just follow it along.