Table 4-4 Gps/Sbas Messages - Garmin GTN 725 Maintenance Manual

Alert Text
GPS NAVIGATION
LOST - Erroneous
position. Use other
navigation source.
GPS NAVIGATION
LOST - Insufficient
Satellites. Use
other navigation
source.
GPS RECEIVER-
GPS receiver has
failed. Check GPS
coaxial for short.
GPS RECEIVER -
GPS receiver
needs service.
GPS RECEIVER -
Low internal clock
battery.
GPS SEARCHING
SKY - Ensure GPS
antenna has an
unobstructed view
of the sky.
LOSS OF
INTEGRITY (LOI) -
Verify GPS position
with other
navigation
equipment.
190-01007-01
Rev. 5

Table 4-4 GPS/SBAS Messages

Possible Cause
An internal position warning
has occurred.
RAIM has determined that
the info from one or more
GPS satellites may be in
error.
There is no GPS fix available
or the system is in dead
reckoning mode.
The GTN is not receiving
data from the GPS antenna.
The GPS receiver has
detected an internal failure in
its GPS receiver.
The GTN has detected a low
battery. Almanac data may
have been lost.
The GTN is searching the
sky for GPS satellites.
Antenna shaded from
satellites.
Corrective Action
Ensure the aircraft has a clear view of the sky.
Wait for GPS satellite geometry to improve.
• Check GPS antenna and cable connections.
• Ensure the aircraft has a clear view of the sky.
• Check GPS antenna and cable connections.
• Check GPS antenna and cable for shorts or
grounds.
• Replace the GTN. Refer to section 5.1 for
details.
Replace the GTN. Refer to section 5.1 for details.
• Check GTN battery security and orientation.
Refer to section 5.5 for details. Cycle GTN
power.
• Replace the battery. Refer to section 5.5 for
details. Cycle GTN power.
• If the message persists after battery
replacement, replace the GTN.
Refer to section 5.1 for details.
• Check the aircraft is positioned outside with a
clear view of the sky. Under normal conditions,
the message should clear after approximately
20 to 30 minutes and not reappear after
cycling GTN power.
• If the message persists without interruption for
approximately 20 to 30 minutes, clears, and
then reappears after cycling GTN power,
replace the GTN battery. Refer to
section 5.5 for details. Cycle GTN power.
• If the message persists after battery
replacement, replace the GTN.
Refer to section 5.1 for details.
• Check GPS antenna and cable connections.
• Make sure the aircraft is clear of hangars,
buildings, trees, etc.
GTN 725/750 Maintenance Manual
Page 4-6