Do you recognize this connection?

[GustaGo]

I started looking into installing rear speakers into my boxster 2004 (HiFi system, speakers in front and doors) and found this connector on the driver side (picture 1); at first I thought it was the connector for the rear defroster but the I founded connected already (picture 2).

I searched the internet, forum and other forums, I also “tried” (emphasis on trying!) to read the convertible top electric diagram but couldn’t find out what it is, do anybody know what it is supposed to be connected to? Thanks in advance

Picture 1

Picture 2