Courtesy Lamp: Description and Operation

GF82.20-P-3002R Dimming Interior Lights, Function

The dome lamp (N70e1) is operated dimmed. The overhead control panel control module (N70) controls the power of the lamps when switched on/off
^ When switched on, the lamp is increased to full power within 1 second.
^ When switched off , the lamp is reduced to minimum power within 3 seconds.

Exceptions
If an ATA alarm is triggered, the lamp is switched on immediately without dimming . If an undervoltage or overvoltage exists, the lamp is switched off immediately without dimming .
As soon as the correct voltage is restored, the lamp is switched on without dimming.