Garmin G1000 Maintenance Manual page 89

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5.7.2 GRS 77 Related Alerts
Message
AHRS TAS – AHRS not
receiving airspeed.
AHRS GPS – AHRS using
backup GPS source.
AHRS GPS – AHRS not
receiving backup GPS
information.
AHRS GPS – AHRS operating
exclusively in no-GPS mode.
AHRS GPS – AHRS1 not
receiving any GPS
information.
MANIFEST – AHRS software
mismatch. Communication
Halted.
AHRS MAG DB – AHRS
magnetic model database
version mismatch.
5.7.3 GMU 44 Related Alerts
Message
MANIFEST – GMU1
software mismatch.
Communication Halted.
HDG FAULT – AHRS
magnetometer fault has
occurred.
G1000 System Maintenance Manual
190-00907-00
Cause
The GRS 77 is not
receiving airspeed
information from the GDC
74A.
GRS 77 is using a backup
GPS source.
GRS 77 is not receiving
backup GPS information
from either GIA 63/W.
The GRS 77 is operating
in the absence of GPS.
GRS 77 is not receiving
GPS data from either
GIA 63/W.
The system has detected
an incorrect software
version loaded in GRS 77
#1.
The system has detected
a magnetic model
database version
mismatch.
Cause
The system has detected an
incorrect software version
loaded in GMU 44.
A fault has occurred in GMU
44.
Solutions
•
Check GRS #1/GDC 74A
interconnect.
•
Replace the GDC 74A
•
If problem does not clear, replace
the GRS 77
•
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.
Troubleshoot GPS problems using
Sections 5.1.2 and 5.6.5.
•
Replace the GRS 77.
•
Load correct software version in the
GRS77.
•
Reference Garmin SB 0533 for
update instructions.
Solutions
•
Load correct software version in the
GMU44.
•
Check GMU 44/GRS 77
interconnect for faults.
•
Replace GMU 44
•
If problem persists, replace
GRS 77
Page 5-53
Rev. B