I have a similar problem with my 2015 ST Limited. AM stations pop in and out, even local ones. (I mean, they suddenly get louder and softer.) It's not ignition noise, nor power line noise, those are different. The most noticeable effect is that the stations seem to be almost fluttering, more like a shortwave station! Sometimes there would be alternator whine, especially when changing gears. Yes, it's an SE-5.
I waited until it was happening all the time and took it to the dealer. Their first "solution" was to switch to FM. "No, we've gotta do AM," I said. And loud! They soon found it was a loose antenna nut, supposedly causing all of my symptoms. When they brought it back, it was working fine. For about a week, then every once in a while, the same thing would happen.
Last week it was again too bad to ignore. When I got home from my ride, I turned the engine off. Pure sound, until I touched the antenna, and got the same popping effect.
Should have done that sooner, I guess, but the antenna had felt tight. Now, when I pull it back and let go, the sound pops with the antenna swing, really neat effect.
I phoned the dealer. Of course as soon as I told them what was happening, they said bring it in, they knew what to do.
But here's the question I asked them, and now ask the Forum. Is a simple antenna nut that hard to tighten so it will stay tight? Loctite is not a good conductor, so I would have thought they'd be relying on lock washer teeth cutting into clean, bare metal as their first line of defense. Then a chase nut or some other way to keep things tight, perhaps?
) check all the connections yall can safely get access to. A go pro could be handy but not worth cost just for this. 
Just few ideas to consider. :thumbup:
pps
