I would love to have that feature! Not sure why... Just seems like a great lighting mod for the sticks and back roads. You should be able to run your own wiring. Here are the diagrams and component locations: 95 850 - Beam Width Adjusters.pdf I'd probably mock it all up on a bench first, then get to...

As mentioned, you should at least be able to hear it.
On my ‘98, it’s pretty noticeable. Kind of a cross
between a giant rogue hard drive and a very
excited squirrel that got ahold of some meth.

Also worth mentioning that it only engages
at under 25 mph.

I haven't had to tackle this particular job, but I have repaired a ton of jamb to door harnesses in a wide variety of vehicles. In my environment, the fix that you'll never have to touch again is replacing the portion of the harness that flexes with better wire. Be sure to go far enough beyond the f...

Have you thought about throwing an
Arduino or maybe a Raspberry Pi at it?

You can also find a speed signal at the
back of the radio, if that helps. It gives
the HU speed for Auto Volume Control.
Black/Yellow, IIRC.

Brown is typically a ground color in these cars.
I don’t have hands on experience with 2000’s,
but I would also suspect it belongs on a bolt.

If it is coming from a piece of wire loom, it might
be helpful to know what other wire colors are
in that section of loom.

A disconnected ground lead could easily show a voltage when measured against a true ground. It’s all a matter of what it’s connected to on the other end. And as far as Volvo using random colors for different things, that idea may apply to some things, but it’s very unlikely that they’d use an establ...

These should get where you need to go:

You seem to be missing the 101/102 combo relay.
105 and 106 are the gray ones stamped “Volvo”.
. .
Swap them and see what you get.

Looks like 101/102 is a Cruise Control module in some versions.
. .
The images shown in this post are for 99’s.

Welcome to SEATAC! With the opportunity of a long layover, I dug a little further into just one part of this little gem - The Turn Arrows. You could be seeing the result of a ground that they share being poor or open. It looks like they share a ground on the 31/50 ground bus on the interior bus pane...