Headlights auto-off glitch

Have owned my 2015 for about a year, no electrical issues. Headlights are stock, and, as far as I know, original.

I've been in the habit of driving w/headlights on day or night, rather than selective use of DRL. Whether or not that makes sense is a different discussion.

I'm used to the headlights shutting off automatically when I open my door. Last couple months though, I've noticed the headlights staying on every once in a while. No rhyme or reason. This really caught my attention when I walked away a few times in a hurry, didn't notice the lights still on, and came back to a dead battery.

User manual says the headlights (and tails) should shut off if the engine switch is in ACC or LOCK and the driver's door is opened. Tested it this morning, and the lights only shut off when in LOCK. In ACC, they stay on.

This only muddies the water as I don't ever have the engine switch turned specifically to ACC. I pretty much park, turn the engine off, open the door and go. Every once in a while I crack the door while the engine's running to check if my 530 AM backup job is crooked or not at work.

So what that test told me is 1) the auto-off isn't functioning right in ACC, and 2) it doesn't reproduce the conditions that led to my lights being left on recently anyway.

This is 100% a first world problem, and easily rectified by just shutting off the lights manually each time. I get it. I'd still like to figure it out in case it leads to other issues down the road. Thoughts?

 

Door switch not telling the ECU it closed...maybe.

 

But then it would happen for both engine switch positions...

 

Something that I figured out with my 06 is that opening the door to turn off the lights is a 1 shot deal. If you open the door with the engine running, and then shut off the engine, the lights will stay on til the battery goes dead. You've already used your 1 shot and no amount of opening and closing the door will make them go out. You have to close the door and turn the truck on and off to get another shot.

 

Totally makes sense, and that explains at least one occasion when I ended up with a dead battery. Still leaves me with the other mysteries though.

 

My lights have stayed on when I went back to roll my windows up after I already turned the truck off.