Table 4-1 Com Lru Failure Annunciation Troubleshooting Guide; Table 4-2 Nav Lru Failure Annunciation Troubleshooting Guide - Garmin GTN 725 Maintenance Manual

Table 4-1 COM LRU Failure Annunciation Troubleshooting Guide

Cause
Aircraft power to COM
board interrupted.

Table 4-2 NAV LRU Failure Annunciation Troubleshooting Guide

Cause
Aircraft Power to NAV
board interrupted.
190-01007-01
Rev. 5
(GTN 750 Only)
Isolation
Check COM circuit
breaker.
Disconnect P1003 from
J1003. Inspect
connector assemblies
and pins. Reconnect
P1003 to J1003. Cycle
power on GTN and
check to see if
annunciation is still
present.
Perform a COM
harness power/ground
test. Refer to appendix
A.3 for pinout
information.
(GTN 750 only)
Isolation
Check NAV circuit
breaker.
Disconnect P1004 from
J1004. Inspect
connector assemblies
and pins. Reconnect
P1004 to J1004. Cycle
power on GTN and
check to see if
annunciation is still
present.
Perform a NAV harness
power/ground test.
Refer to appendix A.4
for pinout information.
Corrective Action
Criterion
COM circuit breaker is
open.
J1003 damaged.
COM harness power/
ground circuit
functioning normally.
Corrective Action
Criterion
NAV circuit breaker is
open.
J1004 damaged.
NAV harness power/
ground circuit
functioning normally.
GTN 725/750 Maintenance Manual
Corrective Action
Close COM circuit
breaker.
Replace the GTN.
Refer to section 5.1 for
details.
Replace the GTN.
Refer to section 5.1 for
details.
Corrective Action
Close NAV circuit
breaker.
Replace the GTN.
Refer to section 5.1 for
details.
Replace the GTN.
Refer to section 5.1 for
details.
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