Mystery Small Rotary Switch

I just became the owner of a 2018 Tundra CrewMax (upsized from a Taco). The previous owner had installed the small rotary dial, pictured below, next to the 12v outlet. Any idea what this might be? I have turned it back and forth and can't seem to find anything that it does. I did find a single small wire (clear blue covering) under the passenger front seat that looked like it was connected to something at one time. The next step is to start removing panels to get to the back of the switch and start trying to trace the wires. Any suggestions on the best way to get to the back of this switch? Thanks.

 

Probably a subwoofer adjustment knob. Blue wire under passenger seat is probably an ACC trigger for an amplifier or the subwoofer it will snake around somewhere and end up behind the head unit most likely.

Previous owner must have wanted their stereo equipment back

 

^^^ This ^^^

That's my guess as well.

 

My guess was leaning that way, with something to do with the amp. I have the JBL system and it looks like the factory amp may have been removed and put back when they sold it. There are alot of wire connectors at the plugs going into the amp. The woofer looks to be factory one, but haven't taken a good look yet (can't fold down the seat backs. Why did Toyota do that? But that is for another discussion). Thanks.