Now this isn't alternator noise. But sound like "ta/ta/ta/ta" which is eminating on occasion from the rear passanger door speaker. (no upgrades to the sustem have been done). I get this sound once in a while, showed up around 3 months ago, and seems to be related to the stereo and that particular speaker.

Any ideas, or anyone have this problem?

 

You should post this queston in our Audio & Video section: https://acurazine.com/forums/audio-video-electronics-navigation-22/

Could this be it?