G900X/G950 Installation and Maintenance Manual – Troubleshooting
Page D-53
190-00719-00
Revision D
D.7.2 GRS 77 Related Alerts
Message Cause
Solutions
AHRS1 TAS – AHRS1 not
receiving airspeed.
The GRS 77 #1 is not
receiving airspeed
information from the GDC
74A #1.
•
Check GRS #1/GDC 74A #1
interconnect
•
Replace the GDC 74A #1:
•
If problem does not clear, replace
the GRS 77 #1
AHRS2 TAS – AHRS2 not
receiving airspeed.
The GRS 77 #2 is not
receiving airspeed
information from the GDC
74A #2.
•
Check GRS #2/GDC 74A #2
interconnect
•
Replace the GDC 74A #2:
•
If problem does not clear, replace
the GRS 77 #2
AHRS1 GPS – AHRS1 using
backup GPS source.
GRS 77 #1 is using a
backup GPS source.
AHRS1 GPS – AHRS1 not
receiving backup GPS
information.
GRS 77 #1 is not
receiving backup GPS
information from either
GIA 63W.
AHRS1 GPS – AHRS
operating exclusively in no-
GPS mode.
The GRS 77 is operating
in the absence of GPS.
AHRS1 GPS – AHRS1 not
receiving any GPS
information.
GRS 77 #1 is not
receiving GPS data from
either GIA 63W.
•
Ensure that a cell phone or a device
using cell phone technology is not
turned on (even in a monitoring
state) in the cabin.
•
Check GPS status for GIA 1 and 2
on MFD - AUX GPS STATUS page.
If one or both GPS receivers cannot
acquire a position lock.
•
Replace the GRS 77.
AHRS2 GPS – AHRS2 using
backup GPS source.
GRS 77 #2 is using a
backup GPS source.
AHRS2 GPS – AHRS2 not
receiving backup GPS
information.
GRS 77 #2 is not
receiving backup GPS
information from either
GIA 63W.
AHRS2 GPS – AHRS2
operating exclusively in no-
GPS mode.
The GRS 77 #2 is
operating in the absence
of GPS.
AHRS2 GPS – AHRS2 not
receiving any GPS
information.
GRS 77 #2 is not
receiving GPS data from
either
GIA 63W.
•
Ensure that a cell phone or a device
using cell phone technology is not
turned on (even in a monitoring
state) in the cabin.
•
Check GPS status for GIA 1 and 2
on MFD - AUX GPS STATUS page.
If one or both GPS receivers cannot
acquire a position lock.
•
Replace the GRS 77.
AHRS1 SRVC – AHRS1
magnetic field model needs
update.
AHRS #1 magnetic field
model has expired.
AHRS2 SRVC – AHRS2
magnetic field model needs
update.
AHRS #2 magnetic field
model has expired.
•
Reference Garmin SB 0533 for
update instructions.