Beautiful drawing!!!! Nice and clear.
The two you had '?' on are power cables; the brown being -, the other is 12V+. The thin black wire in the background, might be the turn-on, but it is not 12V+.
The 12V+ is switched by the vehicle's central electrical system, it is off when the car is in 'hibernation' mode.
what software did you use to sketch that diagram? excellent job!!