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Discussion Starter #1
Hi Guys,

I'm suffering from the well know reception issues and my first port of call was to replace both modules in the C pillar and the trap. I changed them and the problem persists.

However, my reception switches from excellent to static/really poor every few seconds as I drive along. If I happen to park the car in a 'good' signal place the reception is fine and stays fine so it's hard to diagnose!

Am I correct in thinking that there are essentially two FM antennas in the rear screen and the modules switch regularly between one antenna and the other depending on signal strength? If so, it very much feels like one antenna works ok and then it switches to the other which is poor and then back again. It's driving me nuts.

Do these symptoms point anyone to the culprit? I suppose that there is a chance that the modules I've replaced could also be faulty.

Any help would be much appreciated


Thanks
 

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The Diversity system should automatically select the best signal, so it's odd that it changes so much. If you've changed the C pillar modules and it's still the same then it could point to the rear window itself. Does the reception change at all when you put the rear window demister on?
 

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Discussion Starter #3
Hi Richard,

Thanks for replying.
What I've been able to deduce is that the rapid switching is the AF function of the radio switching frequencies to find a better reception.

What I've also been able to do is confirm that the FM1 aerial loop (shared with the AM) at the top corner of the screen is the only aerial that seems to be working. FM2 which uses the upper heating element doesn't seem to contribute in any way. I have confirmed continuity of the FM2 heating element and 12V appears across the element when I switch it on. I don't get any interference when I switch the element on.

Although I've changed the C pillar modules I have swapped them for second hand ones so they could also be faulty, I suppose.

Does anyone have a pair of working c pillar modules that I could use to diagnose? They are quite expensive to buy new and I don't want to replace them unnecessarily.

Thanks
 

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Discussion Starter #4
This weekend I swaaped the diversity module in the left hand C pillar with yet another one, just in case I'd bought a duff one off eBay the first time. No difference.

I'm really scratching my head now. The rear screen seems fine and continuity measures our OK. I really need some suggestions as I'm loathed to buy a new radaio module or rear screen if they aren't the cause of the problem.

If I can narrow it down to one area I can focus on that. Does anyeon have a functional block diagram of the diversity electronics or a good working understanding of the system?

Pleeeaaaassseee!
 

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Hi Guys,

I'm suffering from the well know reception issues and my first port of call was to replace both modules in the C pillar and the trap. I changed them and the problem persists.

However, my reception switches from excellent to static/really poor every few seconds as I drive along. If I happen to park the car in a 'good' signal place the reception is fine and stays fine so it's hard to diagnose!

Am I correct in thinking that there are essentially two FM antennas in the rear screen and the modules switch regularly between one antenna and the other depending on signal strength? If so, it very much feels like one antenna works ok and then it switches to the other which is poor and then back again. It's driving me nuts.

Do these symptoms point anyone to the culprit? I suppose that there is a chance that the modules I've replaced could also be faulty.

Any help would be much appreciated


Thanks
Hi - Interested to see how you get on with this - My FM reception has been getting worse and worse. I know in the UK the government has been busy over the last 10 years selling off any bit of radio spectrum they can and seemingly lowering the power output of radio transmitters to fit more in... BBC Radio 2 is only clear station I can reliably get. I'm thinking I may also have a tired antenna module. I don't get the alternating however - mine is always crap!

Simon
 

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Discussion Starter #7 (Edited)
Curiously, and as part of my investigation, I fired off an email to these guys in California
Hi-Tech Electronics
7049 Valjean Ave.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com<img src=" /><o:p></o:p>
Van Nuys, CA 91406<o:p></o:p>

I explained my symptoms and they confirmed that the radio module was faulty. But the cynic in me thinks they would say that, wouldn't they?

In the interim I have bought a fakra adapter and I intend to try an external aerial plugged into the module in the hopes I can eliminate the module or aerial system.
 

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Assuming they repair radios, yes, I guess they would!! Have you tried contacting a guy called Baris? He goes by the forum name xKaLiBaR or e-mail at [email protected], he repairs and upgrades radio modules, he's based in Enfield.

If it is the radio, it's simple to prove by just swapping it out.
 

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Discussion Starter #9 (Edited)
Thanks for the info about Baris. I'll contact him.
I would definitely be interested in trying our another radio module to help with the investigation. Would I have to find one that is totally identical or would any old BM54 do the trick? Do you have one? I would be more than willing to cover all postage costs and provide a deposit etc if you have one.

Thanks for your help thus far


Matt
 

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Discussion Starter #10
I contacted Baris who actually has a presence on eBay trading as Carphonics. He was very helpful and is able to loan me a BM54 to try. He does think the module is at fault.

I will update again when I know more
 

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Hi

Just seen your message on eBay. It has to be either the radio module, the aerials or the screen and I would agree that it sounds like the radio module is at fault.

I will have a BM54 available from 18th october but if you wanted one earlier I'm sure there are lots on eBay.
 

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Discussion Starter #12
When you say you have one available from the 18th October, what do you mean exactly? You have one for sale?
 

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When you say you have one available from the 18th October, what do you mean exactly? You have one for sale?
Yes. From a 2005 M3. I'll have lots of bits like an MP3 head unit, digital TV etc.

If you don't manage to source one (to keep) by then let me know.
 

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Discussion Starter #16
UPDATE:

I can confirm that the cause of the problem was the BM54 radio module. RichardP kindly loaned me his spare to eliminate the rest of the system and the problem was immediately remedied.

Thanks Richard! Much appreciated
 
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