What the heck is supposed to connect to this ground point?



I tore the tail light assembly apart (for the 5th time) because the passenger side light is sometimes dim when I start the vehicle and a firm knock with my palm usually fixes it temporarily. I am trying to find out why it keeps doing this despite cleaning all the contacts, checking the wires, etc. I can't find anything wrong with the assembly, but this broken ground has been bugging me. I know it doesn't go directly to the tail light because there is no terminal for it. The few pictures I can find online show it drop down into the bumper and out of sight. The electrical schematics re hieroglyphics to me.

Anyone know what is supposed to ground there, and as an aside, anyone have any ideas for the inconsistent tail light issue? I can't find anything wrong!

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2006 Limited CRD: Frankenlift II, Fumoto Drain Plug, DIY Stage 1 Tune, In-Tank Lift Pump

This ground connector looks like it as been added at some point ! Not OEM !