W209 05 CLK Coupe Audio 20 Poor FM reception

[cozzykim]

OK, I've read all the threads I can find, here and elsewhere, regarding poor FM reception.

I have an early 05 facelift W209 (UK RHD), the FM reception isn't as good as I remember it to have been a month ago, I'm getting dropouts and the stations I listen to can't be received in areas where they were OK before.

I've looked at the aerial amp under the headlining at the top of the rear screen; it appears to be properly fixed and all the plugs are connected (as far as I can tell without stripping out the headlining completely).

I've looked at the rear fusebox (left hand of the boot) and checked fuse 8, OK.

I've taken the Audio20 HU out and checked the connections and cables, all appear OK. If I remove the black FAKRA connector the FM signal disappears completely, if I remove the mustard (antenna diversity) plug instead it makes no difference that I can hear.

The central locking is working fine, the range is good, so the R.F. locking pickup in the rear screen appears to be OK.

Does anyone have any ideas what might be causing the low FM signal, I suspect that the diversity antennas might be the problem (does anyone know if there are hidden connectors in the cable for instance), or is it possible that the antenna amp(s?) are not working correctly?

Any suggestions welcome, thanks.

 

[cozzykim]

I've just noticed that the stub "bee sting" aerial on the rear window is missing the screw in part.

Does this form any part of the diversity system, or is it just a phone aerial?

Does anyone have a circuit diagram of the radio/cl/aerial system?

 

[cozzykim]

Feeling a little rejected here

 

[cozzykim]

[solved]

Hi folks,

just in case this is useful to someone, before you start pulling apart your headlining and interior panels looking for the antenna diversity amps, I've found the problem.

I'ts interference from a Griffin (or "Griffin" type) dual usb charger that's been sitting in my ashtray 12V socket for 3 months to charge my phone and dashcam.

Even if the charger is plugged in and not supplying current it affects the radio signal.
When it's charging both phone and cam it squashes the FM signal flat

Without the £$&%£$ thing in the 12V socket, my FM radio works fine, just as it should.

HTH Somebody