New to forum and chasing a gremlin.
2008 Suburban with auto dimming rear view mirror that I understand controls the auto dimming feature in the drivers side mirror. Both mirrors are dimmed and will not un-dim. Visible harness wiring is undamaged and sensors are clean and when tested by shining light or covering them have no affect. My question is, is there a fuse that controls just this feature? I have pulled and checked all the I/P fuses and all are good. If no specific fuse to check, does someone have a wiring diagram for the harness or be willing to post which wires/pins to check for making sure it’* a mirror vs wiring problem. Thanks in advance for your help

As a diagnostic step, have you tried turning the feature off with the power button?

From pages 2-57, 2-49, and 2-52 of your owner'* manual:

Yes I’ve tried the on off instructions, disconnect battery reboot, etc. pretty much everything you can find scouring the web. Looking for a miracle before replacing both mirrors and hoping there’* not electrical issue causing them to fry

Do they go normal with the battery disconnected?

Nope no change with battery disconnect

Unplug the mirror.

I tried that of course. No change. It stays dim

Sounds like the mirror puked.

It’* my understanding the rear view mirror and dimming sensors in it are what control the drivers side dimming as well so can I hope that replacing the rear view mirror may fix the side mirror staying dim? Also is there not a fuse that protects this function? Nothing listed specifically in the fuse diagram and I’ve checked every fuse in the I/P panel and they’re all good.

I think they might be controlled through the door module. Do you have a schematic?
Some manufacturers also have the sensor in the outside mirror.