Originally Posted by sibriggs
I did the update this morning. After reboot the transponder had a big RED X.
Called the G3Xpert line and after discussing the problem it looks like the new G3X software stopped communicating with the GTX 23 box. My latest GTX 23 software was from an Oshkosh visit to the Garmin Booth about 3 years ago. The new G3X software expects to see the latest software on the GTX23, as least that's the conclusion we came to.
As the current update doesn't pass CAN bus updates to the GTX23 the only way to get transponder software current is to remove and take to a shop. Currently waiting on them (local Garmin Dealer) to do the update and see if that fixes the issue. Can't fly with the Transponder out because of ADSB :-(
So if you have a GTX23 that's not current, best to wait to do the latest G3X update until you can update the GTX23 transponder.
Can you power on your GDU in configuration mode and confirm that your GSU 25 successfully updated to software 4.10?