More info on the auto dimming driver's side mirror feature not working.
It appears that my 1SS (likely any LS/1LT) have some wires not included in a couple of the wiring harnesses if the car is not supplied with auto dimming mirrors from the factory. I cannot imagine it's any cheaper to stock/maintain at least two versions of a particular harnesses (2LT/2SS and everything else) than it would be for GM to have one harness with all of the wires present.
I'm getting some greatly appreciated assistance from 2SSRS (Ofer) in getting a revised LCD / backup camera mirror harness that will include the two wires missing from a couple of the GM harnesses that I will run along with the camera power wire down the A-pillar and then into the X207 connector on the left side kick panel area. That's where the wires from the mirror/door come into the car and then just "stop".
At least there's a chance I can get this feature working too.
Thanks Ofer! (2SSRS).