Ranger and F-Series Dome light interchangeability

[RangerReviver1990]

I found this map light/dome light combo off of a '88 f150 at the pick and pull yard the other day and I screwed it into the ceiling of the cab like the original dome light was on my truck with the single (what I'm assuming is the power wire) that one of the screws goes into. But now that I think about it, the f150s light had 2 wires going to it, do I necessarily have to have the second wire. Is that a second wire for a map lights? Or does the single wire suffice?