Garmin GNC 420 Maintenance Manual page 34

MESSAGE
Stored data was lost
Main processor requires service
Memory battery low
No differential GPS position
VLOC remote transfer key stuck
Display backlight failure
COM push-to-talk key stuck
COM has failed
COM needs service
COM transmitter power has been reduced
GPS is not responding
G/S has failed
G/S needs service
GPS stored data was lost
Check unit cooling
No basemap data available
Data card write failure
Poor GPS coverage
Altitude input failure
Page 3-8
Rev. C
Table 3-5. Static Messages
RECOMMENDED ACTION
Replace Main Board (see paragraph 4.5.5)
Replace Main Board (see paragraph 4.5.5)
Replace Memory Battery (see paragraph 4.7.1)
Replace GPS Module (see paragraph 4.5.5)
Replace NAV Receiver (see paragraph 4.5.6)
Replace Inverter Board (see paragraph 4.5.4)
Replace Main Board (see paragraph 4.5.5)
Verify that Mic Key Line is not stuck before
replacing Com Board
Replace Com Board (see paragraph 4.5.4)
Replace Com Board (see paragraph 4.5.4)
Replace Main Board (see paragraph 4.5.5)
Replace Com Board (see paragraph 4.5.4)
Verify that power input to J2-11, 12 has not
dropped below 26 V when transmitting before
replacing COM Board
Replace Com Board (see paragraph 4.5.4)
Replace Main Board (see paragraph 4.5.5)
Replace G/S Board (see paragraph 4.5.6)
Replace Main Board (see paragraph 4.5.5)
Replace G/S Board (see paragraph 4.5.6)
Replace Main Board (see paragraph 4.5.5)
Check Cooling Fan
Replace Map Board (see paragraph 4.5.5)
Replace Main Board (see paragraph 4.5.5)
Replace Interface Board (see paragraph 4.5.2.1)
Replace Flex Cable (see paragraph 4.5.2.1)
Replace Main Board (see paragraph 4.5.5)
Check Antenna and Cabling
Replace GPS Module (see paragraph 4.5.5)
Replace Main Board (see paragraph 4.5.5)
400 SERIES MAINTENANCE MANUAL
P/N 190-00140-05