You know, I'm a former video man, BNC is the key to switch power on !
I hope this stuff is accredited for spinningmagnets and others ?
This is the the key for ignition, it will also provide P+ to light.
I have also a 3 states switch inside the throttle (for real a 2 states switch) that will switch e-brake, nothing or light power.
\./ on off on
ebrake - nothing - light
The light is powered with negative as the e-brake.