190-02207-A2
GPS 175/GNX 375/GNC 355 Part 23 AML STC Maintenance Manual
Rev. 3
Page 5-20
Figure 5-9 GPS/WAAS Alert Troubleshooting
Sheet 2 of 2
GPS searching sky.
Ensure GPS antenna
has unobstructed view of
the sky.
GPS receiver needs
service.
GPS/WAAS Related Alerts
Cause
Corrective
Action
Cause
The GPS/WAAS board is
searching the sky for satellites.
The GPS/WAAS board is
reporting that it needs service.
Corrective
Action
If faults still exist,
contact Garmin.
Approach not active.
Approach guidance not
available.
Cause
The unit did not
have the required HPL/VPL to
get into at least LNAV.
Corrective
Action
Low internal clock battery.
Cause
Corrective
Action
Internal clock battery voltage
is low.
Ensure the aircraft has a clear
view of the sky.
Perform a
GPS/WAAS
Engine Reset
via
Diagnostics > WAAS
page.
Ensure the aircraft has a clear
view of the sky.
Check GPS antenna
installation, connections, and
cable routing.
Wait for GPS satellite
geometry to improve.
Wait 20 minutes for the unit to
complete the satellite
acquisition cycle.
