Reading this thread gives me some hope for getting both of my new mirrors working. I have a 2009 Tahoe, LT 4x4, and it was the DL8 code, so it has power adjust mirrors but no other mirror features. (Well, it may have heated mirrors, at least the wiring to the heater circuit in the mirror body was connected, but this is Phoenix so would probably never have seen it work %^)
Some time ago I knocked the plastic clamshells off the front of the LH mirror. Mirror was fine. Couldn't find the lower clamshell part anywhere. So, I purchased via eBay a new aftermarket replacement mirror (non-towing, puddle light, turn signal, power mirror adjust, power mirror fold). While having done my research to see if that would work on my truck, I learned I'd need a DL3 door window/mirror controller switch, and found a used one immediately available on eBay as well.
Put both of those on my left driver door and immediately I had power fold (manual, via the door switch, not automatic though), the embedded turn signal, and a puddle light. Pretty amazing (at least for me). Power mirror adjust still worked fine. Only thing I needed to do was modify the escutcheon plate inside that has the cutouts for the driver's side door switches (windows, locks, mirror, etc) and a little work with a Dremel tool got that cleaned up. This is cool, I thought.
So I tried the same with the passenger side door. Bought the opposing mirror with all the updated features, and installed it in place of the existing mirror. Almost as before, I had my embedded right turn signal, the power adjust still worked, all good. However, I discovered that I could not get the right mirror to do power fold.
What I'm reading here suggests that I will have to check the RH door harness at the body module for the correct pins, add the wires to the RH side, and maybe have my local tech do some reprogramming of the module. However, I'm guessing on all this since my experience has been different from what most others have found.
Any pointers or actual direction would be extremely appreciated! %^)
Cheers - Jon