Garmin GTN 6XX System Maintenance Manual page 51

Problem
Autopilot is not
getting GPSS/Roll
Steering data from
the GTN (ARINC 429
Roll Steering used).
Tuning data not
updating DME.
ARINC 429 device is
not receiving data
from the GTN.
RS-232 device is not
communicating with
the GTN.
CDI scaling on EFS
40/50 is not correct.
190-01007-A1
Rev. 5
Possible Cause
GTN does not have a position or
flight plan entered.
GTN ARINC 429 output not
configured correctly.
ARINC 429 output port speed not
correct.
Wiring connections are incorrect.
Certain autopilots require
groundspeed for GPSS to be
enabled.
Incorrect configuration.
Wiring connections are incorrect.
Output not configured correctly.
GTN ARINC 429 output not
configured correctly.
Receiving LRU ARINC 429 input
port speed not correct.
Wiring connections are incorrect.
GTN RS-232 port not configured
correctly.
Improper setup on the remote
device.
Device not compatible, or improper
connection.
Multiple TX lines connected
together.
Wiring connections are incorrect.
Baud rate and parity settings not
set correctly.
On EFS 40/50, (prior to SG465
software version 1501) FMS #1/#2
configuration is not set to
"KLN 90-GPS".
System Maintenance Manual GTN 6XX/7XX Part 23 AML STC
Corrective Action
Acquire GPS position and enter a flight
plan.
Check ARINC 429 output port setting for
port to which autopilot is connected.
Check ARINC 429 output port speed
setting for port that autopilot is
connected to and verify that the speed is
correct for autopilot.
Check wiring.
Ensure that groundspeed is provided if
required by the autopilot. This can be
accomplished using GTN Demo Mode.
Check the DME Channel Mode on the
VOR/LOC/GS CDI page.
Check wiring.
Check ARINC 429 output port setting for
port that device is connected to.
Check ARINC 429 input port speed
setting for port that device is connected
to and verify that the speed is correct for
that device.
Check wiring.
Check RS-232 port setting for port that
device is connected to.
Verify the configuration of the other
device.
Verify GTN RX is connected to remote
device TX and GTN TX is connected to
remote device RX.
Verify that there is only one TX source
per RX port.
Check wiring.
Ensure the correct baud rate and parity
settings are selected in Config Mode.
Reconfigure EFS 40/50 for 'KLN 90-
GPS' on FMS #1/#2 inputs as
appropriate.
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