Garmin 20 Pilot's Manual page 130

Appendix
Troubleshooting
118
Problem
POS data flag shows
RTE (Route) flag
ALT (Altitude) flag
LT (Lightning) flag
Possible Cause
Antenna or wiring
Position source wpt
Position source serial data
Interference
Installation setup
Position source route
Serial altitude source
WX500 installation
Action
Check the antenna and wiring
Ensure that a waypoint is selected
as the current destination and a Nav
flag is not shown
Ensure that the serial data output is
configured properly
Have dealer/installer check for any
interference sources
Have dealer/installer check for
proper MX20 setup
Ensure that the external position
source has an active route engaged
Ensure the serial altitude encoder is
powered up and working properly
Have dealer/installer check for
proper installation and setup of the
encoder
If altitude data is provided by an
Apollo GX product, ensure that the
GPS position has been acquired and
a waypoint is selected as the current
destination
Have dealer/installer check for
proper installation of the WX500