I think I figured it out! Here:
Electric Back Light, it's the heated rear window, in glass terms a window is referred to as a light
----This sounds correct b/c my rear window defrost has been out for about a 1/2 year, which means I have not had back up lights for a 1/2 year OMG...
Found the info here:
http://www.dodgetalk.com/forums/showthread.php?t=83091