Rear driver side switch
 

I have a 68 Cadillac Convertible which I just bought. I notice a switch on the side panel next to the courtesy light by the rear driver side seat. I looked at the wiring diagram at it loooks like it might be to disable the cigar lighter but that doesn't seem to make sense. Does anyone know what its function is?
https://cimg4.ibsrv.net/gimg/www.cad...2a5b3a7db6.jpg