klawrence said:
It's the switch to your K40 Radar detector. I have the same model with 2 remotes and one laser defuser except my switch is hidden in the cubby hole and the leds are up by the sunroof switch. When you first turn them on all lights will flash and if you turn the inner switch it toggles between HWY(green led) to CITY(orange led). Your switch is missing a knob, which is to turn the unit on and adjust the volume.
Here's the link.
http://www.k40.com/images/pdf/tech/arch ... sGuide.pdf
Mike `8)