I've been living with a brake noise for the past 7 months and the frequency & loudness have been going up over the passage of time.

The noise started when the car was cold in the morning I'd hear it from time to time when I fully depress the brake pedal. Now I hear it every time I depress the brake pedal while at complete stop. IT IS ANNOYING.

Now, how to verify it's the actuator?
What needs to be changed? Part names/numbers (if possible)?

A diagram of the brake system parts is here: Click here

I need to know what parts need to be changed as I'm going to order the parts and have them shipped from the US to me. So I want to make sure I get every thing I need to have this issue taken care of.

Side question: pardon my ignorance, but what does the actuator do? And why is it producing this noise?

Thanks in advance.

 

I had the same problem with my 2008 LS460L. At first, the dealer told me that it was "just the way the car is." So, I took them for a test drive in my car and then I went for a drive with the same tech in a new car. I pointed out that the new LS didn't make the noise. If the noise isn't there when the car is brand new, it shouldn't be there after a year or two. After I pushed it, I was told that what was called a "Champion Part" was being made for me at the factory in Japan and that it would be here in a month or so. I was told that a new brake actuator was being "hand built" to exact specifications, just for my car. Well, the part came in, the noise disappeared and it stayed that way until I recently traded for a new 2010. As I understand it, Lexus changed the actuator for an updated design, sometime during the 2010 model year. My new car has a build date of 8/10, so I am hoping I don't have the problem again. That said, now that there is a new production part, I would imagine that Lexus will replace it for any customer who squawks about it enough, as long as the car is still under warranty.