Garmin 20 Pilot's Manual page 132

Appendix
Troubleshooting
120
Problem
XPDR flag
ADSB flag
IDENT (green) flag
See the Installation Manual for additional troubleshooting procedures.
Possible Cause
TIS-A Sensor Installation
GDL 90 is reporting that its internal
GPS is not reporting a position or
is reporting an invalid position.
Note that ADS-B broadcasts do not
include position reports when this
flag is present.
This is not a problem. This flag
appears when the GDL 90 is in the
Ident mode.
Action
Ensure that the TIS-A unit is
installed and functional.
Ensure the GDL 90 is installed and
functional. Ensure the GDL 90 GPS
antenna has a clear view of the sky
to receive GPS signals.
None required.