4wd actuator not actuating

unfortunately I’m now realizing I have the least desirable variation. I’d consider myself decent with mechanical bits but this whole electrical thing is really giving me a run for my money

 

You say, the 4WD light came on by itself once?
That can’t really happen. Not without being in 4WD. And not on its own.
The light for the 4WD is gorounded by the 4WD ECM.
It possible it’s the ECM, but it is rare.

like to be sure on the powers and grounds before I’d want to call it that.
Which is why I want to a few more check (above).

 

This was unprompted on the way to work one morning right around when I noticed it stopped working. Popped up after I began driving and went away a minute later. Seems like the only case of this ever.
I have a new ecu on the way from eBay just to check that box but I’ll get back in the truck when I have time this weekend to check the rest of that stuff.