MarioPro

I started hearing a high frequency hum inside my 2017 GX. It is a constant very low volume high-pitched tone that starts when I turn the car on and stops about 5 seconds after turning the car off. I can't hear it at all from outside the car. I was able to isolate it to the speaker/subwoofer in the far rear left side panel just above the jack compartment. Music and other audio sound perfect at all levels from any source. The sound is there even when the audio system is off. It doesn't vary at all with other car systems going on and off like the ac, fans, suspension, courtesy lights, etc. So, I don't think it is a blown speaker or pickup/interference from other electrical sources, or is it? Does anyone have any ideas about the cause, troubleshooting or how to fix?

MarioPro

So, after doing some more research here, I found a similar post. Turns out it was the third row seat warning sound. We never use those seats, so didn't even think of that or remember there was a warning tone for them. One of the seats was slightly raised. Must have hit the buttons while loading stuff into the cargo area or adjusting the second row seats. Anyway, this thread had the answer in this post: