Suddenly degraded FM reception, help!

[Atlanntas]

I'm starting this thread in the 2009+ forum, although I suppose this could also apply to other models. It's here just in case things get specific.

I drive a 2011 6R1199cc BM Polo. Here's a brief description of my audio setup, although it might be inconsequential. The Polo originally came with a RCD210 media unit. I've since picked up an RCD510 second hand around 2015 or so. The latter has two coaxial antenna sockets instead of one, so I just snuck in an adaptor, such as in the picture attached, and carried on.



Fast forward to late last year. During about a span of a day or so, I started getting notable FM reception problems. It has gotten so bad that all I can ever pick up in tunnels or outside city boundaries is only white noise. It's important to note that beforehand the reception was ok. And even better before upgrading to RCD510.

Interestingly enough, if I disconnect the antenna cable so that the adaptor remains attached to the head unit, the reception improves substantially.

I need some tips to troubleshoot this. I have a decent enough electrical/wiring knowledge to do simple mods/installations on the said Polo, but the antennae technology is beyond me . Please help!

[joe6]

This site may help with diagnostics. It is for a mk 5 golf but connectors are the same. http://workshop-manuals.com/volkswagen/ ... t;rcd_510/

The antenna system is also for a golf. This shows the connectors for the RCD210 and further down the RCD510. http://www.my-gti.com/2742/aerial-infor ... lf-mark-vi

If you only had one antenna connector with the RCD 210 then that did not have the diversity function that the RCD 510 has (two antenna connections).
Unless you have disturbed the antenna cable it is unlikely to be that. I would start by checking the radio - try connecting a length of wire to each antenna socket one at a time to see if you get improved reception. My next step would be checking the rear window antenna for breaks in the wire in the window. After that it seems to get a bit more complicated as it could be one of the in-line modules.