On my B&G/Simrad electronics
network, the B&G Zeus was able to tell me everything that was on the network, including stuff like the serial
number. Very handy for diagnosing the issues.
I had two issues that I could figure out by using this information. One was a bad NMEA 2000
T connector, which had been stressed enough to have an intermittent internal connection. Very hard to "see" this without using the chartplotter's page on the network items.
Second, I had a bad masthead sensor, which sort of shorted-out the network. This required more trial and error of disconnecting N2K items until I isolated the masthead as being the problem.
I have found that if you hook up a transducer and simply hold it to your ear, you can hear a tick-tick-tick sound, indicating that it is transmitting. I've also found that you can put a hard surface parallel to the transducer, and perhaps a foot away, and get a reading (an inaccurate reading, but it "hears" the echo nonetheless.
So, start with the diagnostic page on the Vulcan, then see if you have a bad connector or T in your N2K network.