190-02207-A2
GPS 175/GNX 375/GNC 355 Part 23 AML STC Maintenance Manual
Rev. 3
Page 5-19
Figure 5-9 GPS/WAAS Alert Troubleshooting
Sheet 1 of 2
GPS 175/GNX 375/GNC
355 GPS receiver has
failed. Check GPS coax
for electrical short.
GPS navigation lost due to
insufficient satellites. Use
other navigation source.
Abort Approach. GPS
approach is no longer
available.
GPS approach
downgraded. Use LNAV
minima.
GPS/WAAS Related Alerts
Cause
Corrective
Action
Cause
Cause
Cause
A failure has been detected in
the GPS/SBAS receiver.
OR
GPS antenna cable may be
shorted to ground.
GPS Position has been lost
due to lack of satellites.
GPS approach is no longer
available; GPS level of service
is not LPV, LNAV, LNAV+V, or
L/VNAV.
Approach has downgraded
from LPV or LNAV/VNAV and
vertical guidance has been
removed, but an LNAV
approach is still available.
Corrective
Action
If faults still exist,
contact Garmin.
Corrective
Action
Corrective
Action
GPS navigation lost and
may have erroneous
position. Use other
navigation source.
Cause
Internal detection of
erroneous GPS position data
has occured.
Corrective
Action
Verify that the
center conductor
is not shorted to
the braid in the
coaxial cable.
GPS loss of integrity (LOI).
Verify GPS position with
other navigation
equipment.
Cause
Corrective
Action
Improper antenna installation
or coaxial routing.
OR
Antenna shaded from
satellites.
Check GPS antenna
installation, connections, and
cable routing.
Ensure the aircraft has a clear
view of the sky.
Wait for GPS satellite
geometry to improve.
Ensure the aircraft has a clear
view of the sky.
Ensure the aircraft has a clear
view of the sky.
Ensure the aircraft has a clear
view of the sky.
Ensure the aircraft has a clear
view of the sky.
Wait for GPS satellite
geometry to improve.
Wait for GPS satellite
geometry to improve.
Wait for GPS satellite
geometry to improve.
Perform a
GPS/WAAS
Engine Reset
via
Diagnostics > WAAS
page.
Perform a
GPS/WAAS
Engine Reset
via
Diagnostics > WAAS
page.
Perform a
GPS/WAAS
Engine Reset
via
Diagnostics > WAAS
page.
Perform a
GPS/WAAS
Engine Reset
via
Diagnostics > WAAS
page.
Perform a
GPS/WAAS
Engine Reset
via
Diagnostics > WAAS
page.
