190-01007-A1
System Maintenance Manual GTN 6XX/7XX Part 23 AML STC
Rev. 5
Page 5-11
5.3.1.2 GPS/SBAS Related Alerts
Table 5-4. GPS/SBAS Alert Troubleshooting Guide
Alert Text
Possible Cause
Corrective Action
GPS RECEIVER -
GPS receiver has
failed. Check GPS
coaxial for electrical
short.
A failure has been detected
in the GPS/SBAS receiver.
Verify that the center conductor is not
shorted to the braid in the coaxial cable.
Contact Garmin technical support for
assistance.
GPS antenna cable may be
shorted to ground.
LOSS OF
INTEGRITY (LOI) -
Verify GPS position
with other
navigation
equipment.
Improper antenna
installation or coaxial
routing.
Check GPS antenna installation,
connections, and cable routing. The GPS
antenna must be mounted on top of the
aircraft.
Antenna shaded from
satellites.
Make sure the aircraft is clear of hangars,
buildings, trees, etc.
RF interference at 1575.42
MHz from VHF COM.
Move GPS antenna further from the COM
antenna. Add a 1575.42 MHz notch filter in
COM coaxial. Fix or replace the COM.
Disconnect the ELT antenna coaxial to check
for possible re-radiation.
GPS NAVIGATION
LOST - Insufficient
satellites. Use other
navigation source.
There is no GPS fix
available or the system is in
dead reckoning mode.
Wait for GPS satellite geometry to improve.
Ensure the aircraft has a clear view of the
sky.
GPS NAVIGATION
LOST - Erroneous
position. Use other
navigation source.
An internal position warning
has occurred.
RAIM has determined that the info from one
or more GPS satellites may be in error.
Ensure the aircraft has a clear view of the
sky.
GPS RECEIVER -
Low internal clock
battery.
The GTN has detected a
low battery. Almanac data
may have been lost.
Replace the battery.
SEARCHING SKY -
Search-the-sky in
progress.
The GTN is searching the
sky for GPS satellites.
Wait 20 minutes for the unit to complete the
cycle or until the current position is located.
