PURPOSE: To use 12V spec. by connecting each 12V spec lamps in series by means of a main selection lighting switch and a dimmer selection lighting switch in a car of 24V specification.

CONSTITUTION: In a car of 24V specification, 12V battery B1 and B2 are connected in series to make 24V power supply and head lamps ML and MR of 12V spec unit type I , and head lampl ML, DL and MRDR of unit type II are each connected in series to a 24V terminal A through a fuse 7, and in each midway, lighting switches 9 and 10 for main selection and dimmer selection are interposed and those lamps are connected to the middle point C of batteries B1 and B2 through a fuse 8. When a switch 9 is ON, ML, MR, DL, and DL and ML and MR of MR DR are lighted, and when a switch 10 is ON, dimmer lamps DL, DR are lighted. When a fuse 7 is cut, MR or MRDR are lighted through a fuse 8. Accordingly, 12V spec lamps sold widely in the market can be used freely.