I think I figured it out! I didn't get a notification that your post was updated with a link to the manual, only seeing that now when I am posting solution. I'm not sure the forum kicks off an email for post edits.
Anyways, I found the manual online and it contained a test for the optical sensors:
1. Remove ice bin from compartment[br]
2. Close the left door (Door switch pushed)[br]
3. Wait 3 minutes[br]
4. Open the freezer door and keep it open[br]
5. Push the refrigerator button and lock button at the same time.[br]
[br]
If the display says ETY (Empty) then the ice detecting sensor is good.[br]
If the display says FULL then the ice detecting sensor is bad.
Mine was always reporting FULL even though no bucket or bucket empty.
The wiring diagram shows Bright Orange/White (BO/WH) and Red/Yellow (RD/YL) go from each of the optical sensors to the main PCB. I checked for continuity on the connector behind the ice maker (that the ice maker plugs into) to the harness that comes out of the top of the left door. Only BO/WH had continuity - NOT RD/YL! This wire is for the IR LED on the optical sensor to tell if the bucket is full.
So I used some electronics breadboard wire to temporarily run a wire by shoving the breadboard wire pin into the back of the ice maker harness, and the other end into the back of the harness coming out of the left door. And for the first time in WEEKS the refrigerator properly reports that the ice maker is EMPTY!
I won't know for a few hours if it will harvest the ice, but this is very promising!
The wire must be broken inside the door, as all the parts of the wiring harnesses that are visible look fine. Does this mean permanent solution is a new left door? Right now I have my bodge wire running precariously.
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