This sounds like the very common brake booster check valve problem. See my post from last year which contains a link to a Lexus TSB about this. Easy fix provided they use the new updated part. I had mine fixed, now is good. Sound like an electricle sizzle or buzz when the brake pedal is pressed lighly when parked for example. The sound comes from behind the instrument panel.

Taken from the TBS (#L-SB-0074-09): :Some RX 330/350 vehicles may exhibit a rattle or buzz type noise coming from the driver’s side instrument panel area. The noise can be duplicated when lightly accelerating and then decelerating, or when depressing the brake pedal with the shift lever in Park and then releasing the brake pedal.
An improved vacuum check valve is now available to reduce this noise."

https://www.clublexus.com/forums/rx-...z-problem.html

 

Thanks for providing such a great info mswilsonuk:

Would this be consider a Lexus RX350 recall?
I just forward the info you provided to lexus tech
and have them look at the issue.

Appreciated!!!!

 

Glad to be of help. I don't think this is classed as a recall since it is just an ongoing ever-present problem (I have heard it on several 2013 loaners that I have had). Just make sure they use the new part. A lot can depend on which tech you get. When I brought my 2012 in the first time the tech test drove and couldnt hear it. The 2nd time I brought it in the different tech did not want to test drive - he knew immedietly what the problem was from my description, but I think did not use the new part - the problem returned. The third time I brought it in I showed them the TSB and requested the new part (which they had to get shipped from Lexus in California) . Now it is fixed -so far so good. Fingers crossed.

In my experience, lexus are very good at doing what they can to fix any issues.

 

Just want to update the for those people who have the same issue that my RX350 has here is the solution,
valable info. was provided by "mswilsonuk". I went ahead and forward the PDF file to the service department.
And no questions asked they went ahead and replaced the brake booster check valve no charged.
Here is the direct link:

http://www.google.com/url?sa=t&rct=j...lbbFKYoZKN--7Q