Mystery Wires (stereo, maybe?), wiring Options

[avocadotom]

I am in the (hopefully) last stages of assembling my ‘72 914 and I’m hoping to install a stereo.

There are two mystery wires coming out of the hole where the stereo would be, although they do not appear to be the negative and positive wires (although I didn’t check if they independently have power to them). Any idea what they might be?

Backstory: I bought this 914 disassembled by a previous owner and I’m new to 914s, so it’s been a journey...

[avocadotom]

Ha! I will totally peel back the wires to see what colors they were originally.

I did a little more digging into this last night and the smaller wire is brown with a white line, and it has 12 V to it with the ignition on.

The larger "brown" wire does not have any voltage. I don't think it's a ground wire either, because when I connect the two wires through a multimeter, I don't see any voltage.

FWIW, the fresh air fan works, so it's hooked up to something. And to make matters more confusing, there are similar wires (larger gauge brown, smaller gauge brown and white) in the harness as well that ARE hooked up to the fresh air controls. You can somewhat see them in the picture below.