lonzo3

My 2009 A4 Prestige w/MMI has stopped receiving AM/FM stations. All I get is the noise due to lack of signal. Sirius works OK as well as all other aspects of the radio. Manual described a procedure to change reception parameters but my radio does not have this menu item. Could be a connection problem with the radio antenna or the radio does have a reception sensitivity switch that I cannot access. Help?

Moviela

Does the rear window heater work? The antenna for AM/FM is the window heater grid. There is an antenna amplifier near the window, and of course the necessary wiring to the head unit.

If the grid is damaged and does not heat, the signal from radio stations cannot get into the amplifier. Possible problems also include loss of +12v to the amp, the amp is destroyed by lightning, or the antenna connector at the head unit came off.

It can be simply a loose or corroded connector at the edge of the glass.

Sometimes people have the window tinted with a metallized mylar film that cuts off the signal.

The satellite radio works because the antenna for that is in the sharks fin on the roof.

One of my Canadian friends tells me BMW's come with rear window heaters standard. Keeps your hands warm when pushing it in winter.

lonzo3

Thanks for the input. I've just crawled out of the trunk and could find nothing that looks like an antenna amp. I assume that it would have to have a coax cable input along with output and power leads. My A4 has 2 electrical component mounts in the trunk. On the driver side is the navigation DVD drive and audio amp; passenger side has fuses and something that I think may be some type of cable interface. Checking the leads from the rear window would require removal of the liner which is a bigger job than I want to tackle. If I knew exactly where the radio antenna was I may be able to pull back the liner in that area and take a look. Thanks again

Moviela

I think it is on the passenger side. It has to be connected very close to the window heater connection. Pry off the cover of the rear pillar. The amp should be under there. About an inch wide, 3 or 4 inches long.

erw

I had a problem with my radio suddenly not receiving AM. FM and SAT still worked. If I increased the volume up very loud while set to AM, I could hear the station faintly and with a lot of static. I did a little troubleshooting and concluded that the antenna amplifier under the D pillar was probably bad. I exposed it and pressed around on it while set to AM, and the station came in and out. This indicated to me that something was wrong (probably circuit board cracking) with the antenna booster. I replaced the booster and my AM radio reception returns.

The GPS/NAV and SAT antennas are in the roof-top sharkfin. The AM/FM antenna is in the rear window. Some of the on-glass wires at the driver side top are for the radio antenna. There are also some on the passenger side top, but on my model (A4 B8 Premium Plus without NAV), the passenger side antenna leads off the rear window is unconnected.

Under the D pillar on the driver side, you will find an antenna amplifier (aka antenna booster). There is a blue coax input that comes from the sharkfin roof antenna, a lead with a couple of wires coming from the rear window antenna, and another lead also to the rear window grid. This last may be for power. I am not sure. There are two coax outputs, one yellow and one white. I presume there go to the radio unit.