Garmin G1000 NAV III Line Maintenance Manual page 51

ADC
PHOTOCELL A, B: Shows the input value of display photocells, between 0 and 9999. The values can be
converted to a percentage by adding a decimal place two digits over from the right (Example:
8035 = 80.35%). If there is a significant split (~30% to 50%) you can expect the display to appear different from
the other display in the aircraft, IF both of their lighting curves are set to the same values. Replace the display if
one photocell reading is significantly different from the other.
BEZEL THERM: Shows the temperature of the GDU bezel, expressed in degrees Celsius.
CCFT CRNT 1, 2: Shows an indication of current flowing through the display backlight bulbs. Number does not
reflect actual current value and is not useful for troubleshooting.
POWER (2.5V, 3.3V, 28 V 1, 2; 1.3V): Shows power input voltages of various internal components. (Example:
for 2.5V field, 2500 = 2.500 Vdc; for 28V Field, 3633 = 36.33 Vdc) They need to be within 10% of desired
voltages. Replace the display if these values are more than 10% from the desired voltage.
LGHT BUS DC, AC: Shows input value of AC and DC lighting bus inputs, depending on which is configured.
Disregard number if not used in the installation.
INTRNL TEMP 1, 2: Shows the internal temperature of the GDU, expressed in degrees Celsius.
TEST
IIC EEPROM: Shows the condition of the GDU configuration module EEPROM chip, located in the backshell
connector. It should be green for the PFD and red for the MFD. If it is red on the PFD, check configuration
module wiring and pins for damage before replacing the configuration module.
DATACARD CHKSUM 1, 2: Requires the use of a special datacard. Tests the datacard reader interface function.
Used for Garmin testing, not useful for troubleshooting.
NAND, NOR FLASH, SDRAM: Shows the condition of various GDU internal components.
A429 LOOP 1, 2: Indicated the status of the GDU 104Xs ARINC 429 channels. A green box indicates the
ARINC 429 loopback tests passed. A red or black box indicated it may not be used or a wiring fault is present.
ETHERNET 1, 2, 3: Indicates status of the GDU 104Xs Ethernet channel. A green box indicates the ETHERNET
loopback tests passed. A red or black box indicates it may not be used or a wiring fault is present.
RS-232 1, 2: Indicates status of the GDU 104X's RS-232 channel. A green box indicates the RS-232 loopback
tests passed. A red or black box indicates it may not be used or a wiring fault is present.
IRDA: Indicates status of GDU 104X IrDA infrared port. Used for Garmin testing, it is not activated at this time.
BKUP CAPS : Indicates status of the Backup Capacitor Test. A green box indicates the test passed, a red box
indicates it failed.
G1000 Nav III Line Maintenance Manual Page 2-23
190-00352-00 Rev. L