[GeorgeSFNM]

The light has only one wire and is apparently self grounded. When I connected a 12 Volt battery to it I got not result. Does one have to connect the neg . terminal to another wire and that to a ground? Sorry, I'm a candidate for "Wiring for Dummies" book.

 

[rleffler]

Does one have to connect the neg . terminal to another wire and that to a ground? Sorry

Yes, you need a complete circuit. In most cases, lighting is grounded through the airframe, which is also connected to the negative terminal of your battery.