Turbo Boost guage

[cudjoekeytom]

My turbo boost guage isn't working. It worked during my recent trip
from Cincinnat to Orland area, but was not working when I picked it up
to take it to Detroit Deisel Allison. The guage is operated by a line
or hose that runs from the turbo to the guage. FLDDA says it
is "probably" a brake in the hose, but they can't say where.

Any ideas as to where this hose runs and how to diagnose?