Source of poor FM Radio Reception identified - Thoughts?the FM radio?

  1. Schmullis

    Schmullis Senior Member

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    I learned today that if I press on my brake pedal, apply brake hold or activate the emergency brake while the FM radio is playing, the FM radio signal is overwhelmed by loud static. My guess is that this may be caused by a grounding issue.

    Does anyone have a thought how to fix this issue to eliminate the brake caused static effect on the FM radio reception?
     
  2. SCOPESYS

    SCOPESYS Senior Member

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    I have heard reports of LED brake light causing this issue.

    Do you get the interference, if you are stationary, and apply the brakes. ?
    Does it make any difference if you do so this with engine running or not. ?
    Does the Interference level vary by the speed you are traveling when you apply brakes ?

    If you can determine the source of the interference, then finding a solution should not be that difficult. (maybe some sort of RF filtering on the brake lights +12v supply, at the brake light end - or maybe the static is being cause by the actual brake shoe on the rotating brake disk ? ).

    Don't forget the obvious.. a poor/lose antenna connection somewhere, resulting in a low level radio signal, and that is being drowned out by something generating static within the car, that would not be so significant, if the signal was stronger. (specifically on the AM band)
     
  3. napciv

    napciv Insta: Si.Sleep

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    I have the same exact issue.
    2018 Si
     
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    Schmullis

    Schmullis Senior Member

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    Great questions. I did put blinking brake lights in. Never used FM radio prior to that change. I was using satellite radio with no issues.

    Only happens with engine running. Noise present when brakes activated whether stopped or moving. Interesting that it happens when brake hold and parking brake activated -where brakes lights are not activated.
     
  5. SCOPESYS

    SCOPESYS Senior Member

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    Why not put the originalbulbs back in and see if that stops the issue.
    If so, and you still want the Blinking Led lights, then them causing interference with the FM radio would need to be addressed, OR only use Satellite radio , mp3 players or streaming.

    Where I am, you don't want to listen to the local FM stations in any case... at least, I don't :p
     
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    Schmullis

    Schmullis Senior Member

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    Confirmed that the issue is the LED blinking brake light bulbs. Same thing happens with my wife's Camry Hybrid, but not as severe in her car. I stopped listening to Satellite cause I didn't want to pay for the privilege. I do listen to music on my phone via Bluetooth or USB cable. FM is nice to listen to public radio (WNYC) to and from work for my 5-10 minute drive. Does anyone know if a line filter of some type would solve this issue?
     
  7. slowride

    slowride Senior Member

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    Nothing is going to solve the issue because it is the bulbs themselves typically. What brand?
     
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    Schmullis

    Schmullis Senior Member

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    Blinking Light Bulbs brand
     
  9. slowride

    slowride Senior Member

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    Maybe contact them and ask if they have heard of it. Possibly get a new set from them and see if it just those specific ones but if the Camry does it too, it just might be how they are made. I don't think these lights are regulated and could just be designed in a manner that is throwing a lot of junk out there when lit up.
     
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    Schmullis

    Schmullis Senior Member

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    Good points. I did email them today. My civic is a lease with two years left. I'll live with them till I turn it back in. Next time I'll probably just get the center rear brake light flashing module instead!
     
  11. SCOPESYS

    SCOPESYS Senior Member

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    ANYTHING I SUGGEST HERE, YOU DO AT YOUR OWN RISK

    Yes, in theory, a RF line filter could stop any interference from the Electronics in the Led units, from traveling back down the positive 12 supply line , which COULD be acting as a Transmitter Antenna for the RF being generated by the LED unit
    BUT
    The interference might be radiating from the Led unit itself, so it may need to be RF screened.

    Difficult to tell which, or if both are contributing to the issue.
    Only way to find out is to try both correction methods ..

    One thing you could do to determine if the LED unit itself is the transmitting item, is to connect the LED to a separate 12v supply, and then connect a wire between the -ve of that supply and the car earth (ie neg ground of where the led unit connects).

    If you still get interference, then it is being transmitted directly from the unit, so that would need to be corrected with shielding. Something you could probably do yourself, using thin copper sheet, formed around the unit, grounded to car ground.
    Does not need to be that thick, (less than 1mm, so it is easy to bend, not so so thin that it bends too easily by itself. Aluminum foil would not be so good, it will corrode far too easily over time, and is not rigid enough to maintain shape, that could cause shorting issues etc

    https://www.ebay.com/itm/5-pack-of-...v:sc:USPSPriorityFlatRateEnvelope!21087!US!-1

    Even so, there still might also be RF going down the +ve wiring lead, and that would need some sort of online RF filter... maybe as simple as passing the wire a few times through one or more "ferrite core", like you see on some computer video leads etc.

    https://www.ebay.com/itm/20-Ring-Co...283120&hash=item3b074912f7:g:4i0AAOSwWyRau4U9

    so most likely problem can be fixed for about $15 - $35 :)
     
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