G900X/G950 Installation and Maintenance Manual – Troubleshooting
Page D-55
190-00719-00
Revision D
D.8 GDC 74A Related Alerts and Problems
D.8.1 Common Problems
Symptom Recommended
Action
Altitude is different than
standby altimeter
•
Perform a pitot/static check. Allow the GDC 74A to warm up for
fifteen minutes before checking accuracy, per Garmin Service
Advisory 0606.
•
Determine which instrument is outside limits and recalibrate or
replace. Note: Both units may individually be in spec but show a
difference in altitude. Do not return a GDC 74A to Garmin for
service if not outside limits.
•
If GDC is outside limits, recalibration may be performed.
GDC 74A Config file does not
load.
•
Replace GDC 74A config module.
•
If problem persists, replace GDC 74A config module wire
harness.
D.8.2 GDC 74A Related Alerts
Message Cause
Solutions
MANIFEST – GDC 74A#1
software mismatch
Communication halted.
The system has detected an
incorrect software version
loaded in the GDC 74A #1.
MANIFEST – GDC 74A #2
software mismatch
Communication halted.
The system has detected an
incorrect software version
loaded in the GDC 74A #2.
•
Load correct software version.