Ground power - how to programmatically know if ground power is on?

[slughead]

Context: I am writing a tool that exports simulation data to a Thrustmaster Warthog HOTAS throttle controller. Amongst other things, it can control the backlight brightness of the Warthog in response to the F/A-18C "consoles" dial.

I would like to know how to determine via lua scripting whether "ground power" is on or off. Thus when it is on, and by checking other simulation data, whether or not to illuminate the Warthog backlight. So far I have not been able to find anything to indicate this state.