So I've had a 2004 C4S for a couple of years, and I've always wondered about a mod done by the previous owner. I was hoping the collective expertise here at RennTech might be able to shed some light on it.
There is a small switch of some kind on the carpeted side of the upper center console by the driver's right knee (two pictures attached). The switch is wired to a tiny speaker hidden in the A pillar trim to the left of the driver's head (pulled down from the trim in the attached picture). There are two moving parts on the switch. The center knob controls the volume on the speaker. The outer ring is a dial that rotates one click in either direction from center. If the outer ring is rotated in either direction, the speaker makes a sound like a radar detector turning on, and then beeps once every five seconds. There is no obvious difference between the clockwise and counterclockwise settings. When the outer ring is clicked to the center, the speaker is silent, and whatever it is appears to be off.
Other than these two things I don't have any visual evidence (for example, I can't find a detector hidden anywhere). Any ideas? Eventually I will get curious enough to tear everything apart and follow the wires, but I was hoping for suggestions first. Sorry for the poor cellphone picture quality. Thank you in advance for any thoughts.