I'm having a problem with my TZ3 display and my SCX-20. All of my firmware is current. I have setup my SCX-20 as the primary GPS for the TZ3. When I turn on my N2k network, the TZ3 finds the SCX and all is good. However, after a short period of time (less than an hour) it reverts to its fallback GPS. I have several other devices using the SCX and I can watch the PGNs in N2kAnalyzer, and it looks fine. But still the TZ3 seems to lose track of the SCX. Any suggestions on how to debug this?