650 "DATA SOURCE" Message .. UPDATE ..
My first question is what changed and why now? Here is the background and event chain leading to a 650 error Message that was not real.
Discovery - the G3X is much slower than the 650 in the boot cycle. Although I have all the latest (I think SW) the message appeared.
My start sequence is battery-backup on- to boot the G3X then master on and start sequence. Well, my TWC IBBS battery is not charging (2nd failure) and the G3X has not completed the boot before I switched on the avionics (includes the 650). I had already done all my preflight checks and taxied up-shut down for a passenger. The restart sequence was faster than normal cold sequence. And . . I did not wait for the full g3x boot to continue in the checklist switch activations.
Yesterday, I watched the info errors on the G3X and found the RS232 and ARINC 429 connection errors disappear late in the boot sequence as linkage was established. It took longer than I thought. When errors were allowed to clear before turning on the 650 (Avionics), there were no error messages on the 650.
Now what I believe to have happened (but will discuss with Garmin)- - I think that the error generating SW code for the" Data Source: HDG" is encountered and posted to the screen before the data buss connection handshaking is completed, but is not revisited after the connection is made, i.e. is not constantly being checked (?). This allowed my direction up map to display properly but the error message would not disappear even though it was no longer valid. The location of the error message posting location in the line of boot code was before the ARINC could be finished due to the slower speed of the G3X booting process.
Action(s):
1) Charge/Replace IBBS battery.
2) Discuss SW with Garmin as to why the message did not disappear once "source" was connected so others won't get the message.
3) Evaluate panel change to provide more reliable IBBS, and alternative to IBBS to maintain line voltage to G3X in addition to IBBS - i.e. voltage stabilizer.
Thanks for listening.