I would assume that the left wire is not connected. The police bikes come from the factory with a flasher to make the par lights flash alternately. When it was taken out of service they may have removed the flasher.
Work Ride- 2008, FLHTP
2006 Ultra Black Cherry/ Black Pearl
88", Thundermax AT, Andrews 26G
Rush 1.75", K&N Air
Blue Knight Special (#75 of 75)
89" S&S Stroker, Mikuni HSR 42