190-02207-A2
GPS 175/GNX 375/GNC 355 Part 23 AML STC Maintenance Manual
Rev. 3
Page 5-7
Figure 5-2 GPS 175/GNX 375/GNC 355 System Alert Troubleshooting
Sheet 1 of 2
GPS 175/GNX 375/
GNC 355 demo mode.
Do not use for
navigation.
Pilot stored data was
lost. Recheck settings.
GPS 175/GNX 375/
GNC 355
needs service.
GPS 175/GNX 375/
GNC 355 over temp.
Reducing backlight
brightness.
GPS 175/GNX 375/
GNC 355 knob-push
stuck.
System Alerts
Cause
Corrective
Action
Cause
Cause
Cause
The DEMO MODE
input pin is grounded.
P1751-58 on GPS 175
P3752-29 on GNX 375
P3551-58 on GNC
355
The unit detected
errors in the regristries
of pilot stored data.
Reset config and
reconfigure unit.
Cooling fan failure
OR
Cooling fan
obstruction
The inner knob push-
key is stuck in the
enabled or pressed
state.
Corrective
Action
Corrective
Action
Maintenance
Log Message
GPS 175/GNX 375/
GNC 355 needs
service. <condition>
Inspect connectors
and wiring to remove
the signal from the
DEMO MODE input
pin.
Re-check pilot
configurable settings.
Corrective
Action
Check the fan intake
and outlet slots on the
bezel for dust or
obstructions and clean
as needed.
If faults still exist,
contact Garmin.
Corrective
Action
Press the knob to
cycle its operation.
Cause
The GPS 175/GNX
375/GNC 355 has
detected loss of
calibration data or an
internal failure.
Reload software,
Reset config and
reconfigure unit.
Reload software,