L3 comminications Trilogy ESI-2000 Pilot's Manual page 56

Troubleshooting
Corrective Actions
CoNDITIoN
Continued from previ-
ous page.
4-6
(continued)
CAUSE/CoRRECTIVE ACTIoN
2. If an "Inv 429 Input" message is
shown above the heading tape, then
invalid external heading input data is
being received.
• If the LRU providing external
heading input data begins send-
ing valid data, the message is
removed and the heading tape and
digital readout return.
• If the heading tape and readout do
not become active, cycle power to
the ESI-2000 and the LRU provid-
ing external heading input data.
• If the invalidity continues to be ob-
served after power cycle, the LRU
providing external heading input
data may be defective.
3. If a "429 Failed" message is shown
above the heading tape, then the
external heading data is invalid.
• If the heading tape and readout do
not become active, cycle power to
the ESI-2000.
• If the invalidity continues to be
observed after power cycle there
may be a problem with the ARINC
429 connection or the ESI-2000
may be defective. Have system
checked by certified service center.
ESI-2000
Pilot's Guide