2010 Yukon Rear Window Defroster Left Side Not Working

[Buddy67Lincoln]

my 2010 Yukon has power to the right side defroster, not the left. When I jumper the right side directly to the left side it works. Must be the wiring; but is there a relay for the left side only? Fuse? or something? Can't really figure out why the two are not wired together. I followed the wire and the left side seems to follow the right side harness down into the tail gate. The right side goes into the cabin at the top of the door so they are not connected. Is this some safety feature that the door must be down for it to work?

 

I did recently repair the small connector that is glued to the glass. It worked after I used it. I have power to all grids, no broken grids (not that I would think that would cause my issue). There is power around the metal tab mount for the plug but nothing on the tab itself that the plug attaches to. Maybe the glue went bad??? But it did work for a while (maybe 6 weeks or so after the repair).

 

Thank you for any help. I know the working right side is a thick purple wire, the left side is black and at no point can i see what color the wire is inside since it goes down the tailgate on the right side. Did not want to tear into the tailgate any further till I asked what it might be. Thank you!