4304 - Obstructed lights not required.

     § 4304.  Obstructed lights not required.        Whenever motor and other vehicles are operated in combination     during the time that lights are required, any lamp (except a     tail lamp) need not be lighted which, by reason of its location     on a vehicle of the combination, is obscured by another vehicle     of the combination, but this does not affect the requirement     that lighted clearance lamps be displayed on the front of the     foremost vehicle required to have clearance lamps, nor that all     lights required on the rear of the rearmost vehicle of any     combination shall be lighted.