Hi all,
About a month ago, we came into the garage and turned the key to acc spot,which normally everything is very quite, but instead heard a load buzzing noise coming from the rear seat area. At first I thought it was the ant sticking going down, but radio was already off.

Has been doing it about 95% of the time ever since, 5% it is quite.

The Lex dealer had it today and of course it did not make the noise while they were listening .... was making just fine when I drove in yesterday, hate when that happens

Have any of you had fuel pump problems ?

I would not suspect the fuel pump. Normally the fuel pump makes noise as you turn the car on because it primes the fuel rails. It does not continue once you turn it over. I would guess it is something to do with your exhaust system. IMHO....

The Lexus dealer yesterday finally got to hear the noise I was talking about, I stand corrected....not a fuel pump issue.

I was surprised to find out the noise is coming either from the Mark Lev amp cooling fans or the Navigation drive unit, with the sound being intermittent, they are leaning towards the Mark Lev cooling fan.

Should find out more later today.

MH6, I also now and then hear a very faint buzzing sound in my car, but nothing that sounds completely out of line. When the dealer determines the exact source of this noise, please report back. Thanks

I sometimes detect a little whirring from the hydraulic brake pump (in the same module as the master cylinder area) when it's building pressure. You might hear this if you turn the key to the run position without starting the engine? It's difficult to separate from some of the other startup noises but if you listen for it it's noticeable especially with the hood open.

I heard from the dealership late Friday, and it was determined that it is the Mark Lev cooling fans causing the noise. I believe that the entire amp assy has to be replaced, I will know for sure Monday.

This noise is rather well pronounced when the car is shut down and put to the accessory position before pulling the key out. It was very constant for a few weeks and then became a little intermittent, but happened enough in their presence to locate it. The noise would come from the back seat/ trunk area.

I will have the full story Monday.

You are correct, on start up, with key in power position, you will hear the above and a couple of other checks in progress

Lexus got back with me, it is definitely the Mark Lev cooling fan causing the noise ! The entire amp must be replace because the cooling fan is incorporated
as one unit. Amp is approx $450.00 and was covered under my 3rd party warranty, they also took care of the noisy door check...that was a irritating noise as well.

So the visit has been fully covered ! 0 out of pocket

Yeah Baby! Nice to hear about a warranty paying off.

Great news! That's an inexpensive amp! Mine about a year and a half ago was $600. I love these warranties-paying-off stories!