Are you sure you haven't got any fuse issues, as far as i'm aware CAN faults doesn't actually mean a network fault as a power/ground fault can cause CAN network error codes.

I'd remove and manually test every fuse just to be sure as times i've missed the obvious.

CAN isn't something i'm really experienced with but how does only the ipc & bcm log CAN faults as the engine ecu uses CAN to exchange data such as temperature to the ipc and posdibly vehicle speed signal via abs if fitted.

Not sure how easy it is to access bcm harness but could it be possible to temporarily run new can wires between ipc & bcm to see if CAN responds.