I had recently posted a question about this (Active brake lights interfere with radio station on ‘16 Mazda CX-5?) and I ended up removing all the lightbulbs in the car.

After removing all bulbs in the car, I found out that the issue were the brake bulbs: I removed both brake bulbs, then hit the brakes and there's no radio interference.

I then tested by removing one bulb and leaving the other, and hitting the brakes. In both cases (left bulb in and right bulb out, and vice-versa) there's interference, even though the static sound is stronger with one bulb. It's only when I remove both bulbs that there's no interference.

Common sense tells me that both light bulbs are defective and should be replaced. My question: is this conclusion correct? My concern is that I buy and change both bulbs and then find out that the interference still exists.

  • I bet not on the bulb, but on the wiring that powers it.
    – Agent_L
    Apr 28, 2020 at 8:51

1 Answer 1


Had a similar issue once on one car, absolute so and so to deal with.

After fitting capacitors on various circuits, extra earth bonding straps between various panels, what finally worked was to use shielded cable for the supply to the radio. Direct (and fused) from the battery controlled by a relay so it still came on with the acc on the ignition switch.

You might find a judiciously placed capacitor may be sufficient but it does depend on what is causing the interference.

  • Thanks. In my case, the "starting point" are the brake lights because I remove them and the problem's gone. Was your starting point a bulb but in the end wasn't the issue?
    – rbhat
    Apr 24, 2020 at 18:48
  • What the issue was does not matter, the point was to give you possible solutions that you could apply to your situation.
    – Solar Mike
    Apr 24, 2020 at 18:52

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