I was thinking of disconnecting the rear left door speaker, but now that I have tested
by disconnecting the amp for all speakers, does it make sense to disconnect
the rear speaker?
It doesn't seem like it would make any difference.
Thoughts on this?

 

No, there’s not. Remove the trim and disconnect the only speaker there.
You said that you did cover the grill mesh of the speaker. What happened with the noise?

 

It didn't make any difference. The sound was just as loud.
So I'm thinking like this, if the sound IS coming through the speaker,
and it is quite faint, why wouldn't it be much fainter if I placed
a piece of carpet over the speaker (which I did)?

Do you see what I mean?

Is your theory that despite what I said above, it still
might be coming through the speaker and it could be able
to transmit the sound even without being powered
by the amp?

 

No, definitely it’s not coming from the speaker.

 

I think you can understand why I am confused.

Can you please explain why you want me to disconnect the speaker if the sound is not coming from the speaker?

 

I thought it was the speaker, but when you told me that the sound remained the same with the speaker covered then clearly it’s not the speaker.

 

OK. If we have concluded it is not the speaker, does it make sense to disconnect it?

 

Are you sure it is coming from within that area? Before dismantling anything put a blanket over the inside door and see if sound is muted at all. Have you had someone sit back there to try and determine location?

 

No because you already disconnected the amplifier.

 

I had the rather unpleasant experience of hearing a geiger counter noise in my car today. The sound was extremely similar to what @NoiseFree recorded. It was coming from the front of the car but I originally thought from the upper right dash near the window.

It took me a while to pin it down, and I know it's not Noisefree's problem, but it turned out to be a very thin walled plastic cup vibrating in the cupholder in the front console. The rapid clicks were telegraphing into the upper right dash area so that it sounded like it was coming from the right speaker. I was actually changing the radio volume to see if it made a difference before I finally realized what was going on.

The point is that the way cars are made with all the complex moldings and metal structures, noise can travel so the source may not be obvious.

 

It is definitely coming from the back left of the driver's seat.

I tried placing a blanket over the inside back left door today but it had no effect on the Geiger noise!
I don't have anyone at the moment who can assist me in locating the noise.

 

I'm glad you were able to find the source of your noise rather quickly.
Could you imagine having to live with your noise problem for a year as I have?

 

OK, so the rear left door is not the problem.

Now, try to cover the seat, the B pillar, the rear seat...

 

It would have driven me beyond nuts if I had to live with it My mind was racing with possible causes. First thought was "it's a mouse in there" which is bad due to potential rampant chewing damage. We've had mice in the house walls that make a rapid scratching or chewing noise that is kind of click-like.

You need a second set of ears to help pinpoint it.

 

I get it, there’s a certain satisfaction in tracking down and fixing issues yourself. I've been there! But honestly, why go through all that hassle when it’s a brand-new '24 car still under warranty?

My advice would be to schedule an appointment with an Authorized Lexus Dealer. They typically have one or more technicians ride along in the car to accurately pinpoint the source of the sound. Worst case, they’ll identify the problem and have you return another day for repair and/or part replacements. You already paid for this when buying new. Let them handle it!

When I first got my '23 300h, it included a few creaks and rattles in the cabin. I managed to DIY all thanks to the guidance from this forum; particularly the @E46CT guide for the center arm rest. However, there was one intermittent and persistent issue at the rear that I couldn't pinpoint and drove me crazy. I even insulated the trunk and made sure there were no lose parts. It sounded like a faint metal clunk when driving over uneven roads or speed bumps. While it wasn’t overly loud, or consistently present, it was irritating enough in an otherwise very quiet cabin.

During my 15K service, I asked the service advisor to please investigate this issue further. It took them nearly a full day to pinpoint the problem, which turned out to be a defective rear left shock. Apparently, a metal cap within it was causing the noise. They ordered the replacement part, and I returned a week later for the fix. Now, the cabin is finally super quiet, with no more intermittent clunks!