Microsoft Flight Simulator: How to Restore AI traffic Lights after SU5 (Steam Version)

So the problem statement is pretty simple – something changed in Sim Update 5 that broke AI traffic lighting and it appears to be due to the AI traffic not turning on the electrical systems in flight. No electrical system – no lights. Luckily there is a pretty simple fix that only requires you to update the system.cfg file for your AI traffic.

Enter the the file structure for the aircraft you want to add lights to. Under the SimObjects folder…then Airplanes…and perhaps one more layer down for the skin…you’ll find system.cfg. Make a copy of that file so everything you do is reversible.

All you now need to do is copy to following text into the [Electrical] section of the file:
; LEGACY
max_battery_voltage = 24 ; ###
generator_alternator_voltage = 28 ; ###
max_generator_alternator_amps = 60 ; ###
electric_always_available = 1 ; ###
flap_motor = 0, 5, 17 ; ###
gear_motor = 0, 5, 17 ; ###
autopilot = 0, 5, 17 ; ###
avionics_bus = 0, 5, 17 ; ###
avionics = 1, 5, 17 ; ###
pitot_heat = 0, 2, 17 ; ###
additional_system = 0, 2, 17 ; ###
marker_beacon = 1, 2, 17 ; ###
gear_warning = 0, 2, 17 ; ###
fuel_pump = 0, 5, 17 ; ###
starter1 = 0, 20, 17 ; ###
light_nav = 0, 5, 17 ; ###
light_beacon = 0, 5, 17 ; ###
light_landing = 0, 5, 17 ; ###
light_taxi = 0, 5, 17 ; ###
light_strobe = 0, 5, 17 ; ###
light_panel = 0, 5, 17 ; ###

Note: Yes, this replaces ALL of the text in [Electrical].

Save the file and you’re done.

1 – make sure you backup your default system.cfg file – you want to be able to revert if necessary
2 – make sure you don’t do this on your primary aircraft – you will likely lose control of your electrical system
3 – be prepared that things may change in future updates
4 – you may need to tweak the text additions if they don’t work perfectly for your livery