Noisy Radio

[Frankie L]

NOISY RADIO I'm probally asking a question that been asked 100 times, but anyway......here goes. Since we had a nice snow storm in Long Island, New York and while I was driving I had my radio on (2003 325xi) so, when I put on the rear defroster, the radio started hissing like hell, music went dead. When I shut the defroster off, my music came back on. Now I asked ......whats up with that. Are the spark plugs wires the problem or am I missing something.??????

 

[Wadula]

??? sorry dude, but i never heard of that...weird problem....this problem doen´t show up with me...sorry...

 

[Kirby]

I've been thinking about this one - yeah, it's odd. A few questions:
- Did the radio work OK before with the defroster on and this just popped up?
- Does it happen on AM, FM or both?
- I assume it does not happen with a CD?
- Have you noticed weak radio reception in general?

 

[Frankie L]

Kirby...............thanks for the questions. Here are the answers.

From the very first time I put the rear defroster on, it happened. It happens on both AM & FM. Never a problem with radio signal strength. It doersn't happen when the CD is on, just the radio. I never bothered bringing it to the attention of my dealer, since I don't regularly use the rear defroster. It doesn't happen on my 525 just the 3. Who would have thunk it.!!!

 

[Kirby]

Since it doesn't happen with the CD player, the problem is with the antenna circuit, not the audio amplifier, which is what I suspected. Since it occurs on both AM and FM, it's less likely to be some sort of radio frequency noise. If it was RF noise, it would only occur on one band, or sound somewhat different between AM and FM.

The radio antenna is part of the gridwork of the rear defroster on most newer bimmers, except for the ragtops. From what I have seen in the 3 series, there is a signal combiner/amplifier located in the left rear roof post (D pillar) that handles all of this. Assuming the 5 is the same, I'm thinking that unit may be bad or have a poor connection.

 

[Wadula]

do you have an antenna on the rear part of the roof? maybe the antenna line goes parallel to the power line to the rear defroster. voltage in lines create magnetic fields that have an effect on other lines in their vicinity. but that would mean the antenna would have been installed later.

 

[Frankie L]

Thanks Guys, I appreciate the input. The Antenna is part of the window, there is no external antenna. I have to bring the 3 in for Inspection 1 soon, I'll mention the radio to the dealer and hopefully there's a simple fix. Thanks again my friends.

 

[geneo]

it is the rear window or a loose connection at the window behind the left side c pillar cover have replaced many rear windows for the same problem the ant is in the window

 

[Wadula]

i thought the antenna is in the front? well, you never stop learning

 

[dh21187]

I have the exact same problem when I use the defroster. Near as I can tell the current that makes the defroster work is on the same circuit as the radio. The current from the defroster working is what is causing the problem. Somewhere along the way BMW failed to isolate the two from each other properly to stop the interference.