Falls said:There is contact points so when the window goes up they connect . If the rear def. is on and you drop the back window it shuts off. Thats all I know about it. Except for the fact I think they work pretty crappy as far as the heat goes.
On our 00 Tahoe and my old 04 Z71 Tahoe you could damn near fry on egg on that window , it fricken melted everything.