OK so after reading up on this I think the 2008 M3 doesnt have any special passives in the FM antenna harness, it looks like just a long coaxial type cable running from roof to passenger (USA) side and then to the front where it comes up behind the radio and plugs in. Its in 3 different sections that interconnect. I'm convinced Mine has to be unplugged or open somewhere because I can get decent reception with a whip antenna plugged right into the back of radio sticking up out my window. Does the harness go forward above the headliner or does it come up front under the door sill?
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