[Mr70]

Your both right.
The trunk & engine compt. lamps are wired hot,meaning they have power applied at all times.
The engine compt. lamp is wired to the hot side of the horn relay or similar,and the trunk compt. lamp to a hot lead of the rear harness.
Both lamps will light when lifted to the upright position,thanks to the liquid mercury making the final connection.These lamps also flicker intermittently when the car goes over a speed bump or something similar,that jars the liquid mercury into making contact.Drive around with the rear seat back removed at night,and watch how many times the lamp pops on.That's why many remove the light bulbs,as they flicker on & off all day long during driving.