Map light switch

I have a '68 GTS clone vert that I'm trying to determine why the map light under the dash won't work. It doesn't have a map light switch mounted under the dash BUT I can plug the male connector into the cigar lighter female & get it to burn? Rear interior lights in back floor board area work with door switch/dome light on headlamp switch correctly. No map light switch bezel is seen anywhere or hole that would indicate it ever had one. I'm stumped. Thanks for any help!!