The PHILCO Phorum
Auto LED Retrofits causing interference on the car's radio. - Printable Version

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Auto LED Retrofits causing interference on the car's radio. - MrFixr55 - 07-23-2023

Hi Pholks, 

Hopefully I put this thread in the correct category or hopefully the Phorum is the correct Phorum for this topic  Moderators, please correct if I put this in the wrong spot.

Several members and I chatted a while back lamenting how new cars, especially EVs will not have AM Radio.  We did a lot of theorizing about why.  The theory of a noisy EV electric system along with all the other EMI pollution from cell phones, power meters remotely read via carrier current, etc. drew the most agreement.  

Last year, I installed a set of LED Headlight bulbs in my 2003 Taurus.  Some time after that, I noticed a degradation of AM performance and a noisy antenna (static as I went over bumps, attributable to flexing the antenna cable).  When it got to be too much to bear, I installed an automatic power antenna.  I thought it worked great till I actually started the car and the horrible performance returned.  (Long ago, I wired the car for the headlights and taillights to go on when the ignition switch is in run, due to none of my cars having daytime running lights, NY law that lights must be on when windshield wipers are being used, and my propensity to leave the lights on when I leave the car.)

After some troubleshooting, I determined that one of the LED headlights is generating the noise.  The other one does not. 

I will try to put a ferrite bead on the leads to the offending lamp and to the radio to see if that helps.

RE: Auto LED Retrofits causing interference on the car's radio. - DaleHCook - 07-24-2023

Did you swap lamps from side to side to see if the problem is location-specific? Did you buy a major brand of lamp at an auto parts store? Off-brand LED lamps sometimes have not undergone FCC certification for noise generation and are therefore sold illegally in the US. I would return it as defective.

RE: Auto LED Retrofits causing interference on the car's radio. - RodB - 07-24-2023

Ah yes, ferrite beads. My first test in my part-time electronic tech job after retiring I was supposed to cut open the 5 traces for a cable connection of a 1" x 1.5" camera PCB and solder in 0401 SMD ferrite beads. After doing a few of these it was difficult to focus my eyes. But it helped eliminate the noisy cable and produced a clear display. Sounds like you're on the right track and if it works put them on the other side.

RE: Auto LED Retrofits causing interference on the car's radio. - morzh - 07-24-2023

Any LED lamp will have a DCDC switcher current source chip there. Sure enough, it will emit stuff.

RE: Auto LED Retrofits causing interference on the car's radio. - MrFixr55 - 07-26-2023

@ Dale, yes, these are CCC, not Phillips. (They dis say DOT on them but that can be counterfeit. The noise did not come immediately; I have been running these for about 1.5 years. I havenot swapped positions to see if the issue traveled. I would have done that if they were new.

These do perform better than any incandescent bulb that I have used, and no one is flashing their lights at me.

RE: Auto LED Retrofits causing interference on the car's radio. - DaleHCook - 07-26-2023

MrFixr55 Wrote:They dis say DOT on them but that can be counterfeit.

It wouldn't show on the bulbs, but the packaging has to show that they meet FCC Part 15. Unfortunately a lot of LED bulbs have been imported that may say that they meet Part 15, but have either not been tested or have failed those tests.

RE: Auto LED Retrofits causing interference on the car's radio. - MrFixr55 - 07-26-2023

Hi Dale,

They did say DOT on the box. I do not know if they said that they meet FCC Part 15 though. I got them from eBay. They are definitely Chinese, they were not a known brand. Of course, getting something from eBay does not guarantee legitimacy. (There is concern that these gangs that are stealing stuff from drugstore shelves are selling the stuff on eBay.) The real counterfeit stuff is on Ali Baba. (Don't buy a Shure SM58 Mic from them; they are fake.)

However, I will determine if they are emitting interference outside the car by trying a portable radio in front of the car to determine if the lights radiate the interference.