Humming noise after shutoff - 2012 Tacoma 4.0L V-6 5-speed automatic

Hi all,

My truck recently started making a humming noise when I shut it off. This started about two months ago, and seems to have got a bit louder ever since. The noise will stop when I switch the headlights off, or open my door to get out. Seems electrical in nature, but beyond that I have no idea. I've uploaded a video at the drive link below. There's two videos there that are the exact same, one is .mov and one is .mp4.

https://drive.google.com/drive/folders/1Ejlw06-EV9WMT0Q6Dw-j5y1H2ApuUN6W?usp=sharing

Thanks for any insight

 

Probably the exhaust purge system doing it's thing. Do a search, I posted the same question a long time ago!