Installation Instructions

190-01007-A3 GTN 6XX/7XX AML STC Installation Manual
Rev. 4 Page 5-87
5.6.9 Lighting Bus Interface Check
The display and key backlighting on the GTN can track an external lighting/dimmer bus input and use it
to vary the display and key backlight levels accordingly. This check verifies that the interface is
connected correctly.
CAUTION
When 14 VDC or 28 VDC lighting buses are connected to the GTN, connection of the
aircraft lighting bus to the incorrect input pins can cause damage to the GTN. Always
start this test with the dimming bus at the lowest setting, and slowly increase the
brightness. If the LIGHTING level displayed on the GTN does not increase as the
lighting is increased in brightness, verify that the wiring is correct before proceeding.
1. Ensure the lighting bus is set to its minimum setting.
2. Go to the Lighting Bus Configuration page.
3. Slowly vary the lighting bus level that is connected to
the GTN. Verify that the Source Input Level value
displayed on the configuration screen tracks the
lighting bus setting. Continue to maximum brightness
and verify proper operation.
Figure 5-53. Lighting Bus
Configuration Page