Checking vehicle part power usage/production (spec. in veh_interact::cant_do)

I’m trying to make a multimeter item that measures power consumption, power production and possibly charge levels (could replace magically knowing how much charge an item has left with a rough guess, requiring this item for precision?) for vehicle parts and electric items. So far, I’ve set up the json and started adding a new option (‘measure’) to the Examine Vehicle screen, but I can’t figure out how to check whether the selected vehicle tile has a power-producing/using part - and, after this, how to check the properties mentioned above.

What should I refer to for these properties, and is there a better way to implement this item? (The examine vehicle screen seems pretty cluttered, and adding a new action probably won’t help.)