Take the lower outside cover off and look for the wiring diagram. Look at the lower left corner. Compare it to the pic of mine (it's an LBK, not an RBK). Item "K" is the heater cable in parallel with my inside light. If you have a squiggly line like my "K" in parallel with your inside light, you've got the defrosting strip.
1988 Coleman Sequoia - popup (1987-2007)
2012 Roo19 - hybid (2012-2015)
2016 Mini Lite 2503S - tt (2015 - ???)
2011 Traverse LT, 3.6L, FWD
2009 Silverado Ext Cab, 5.3L, 4x4, 3.73
2016 Silverado 2500HD Dbl Cab, 6.0L 4x4, 4.10