Okay...I have a 2000 GS300 with 48,000.(Yes, we almost never drive it) Here's my scenario.....When I'm stopped at a light or and I get this vibrating noise coming from the front somewhere. It sounds like it could be behind the dash or in the engine compartment.

Here is where I get thrown for a loop. This only happens when the car is in DRIVE and the brake is applied and I'm stopped. If I throw it into PARK, the noise goes away immediately. If I let off the brake, it goes away. I haven't tried the other gears yet or reverse, but I am going to try those as well.

Any ideas? I thought it may be a vacuum or something, but I really have no clue.

 

Search is your friend... https://www.clublexus.com/forums/sea...archid=5529775

Its your brake system or rather the electric brake booster motor. Bet if you put it in park and pump the pedal a few times you'll hear it again

 

That sounds expensive.......Is it something I can change?

I will test out the car with it being in PARK.

 

I never said there was anything wrong with it its just making its adjustments... Its a Toyota thing

 

I suppose that is normal. Meaning the ABS motor is activating.

 

I just can't figure out why it doesn't always do it all the time? Sometimes I don't hear it for weeks.

If it was the ABS thingy, shouldn't it do it all the time?

 

no. Just my hypothesis, it only activates after level or pressure changes significantly; thus the reason you have to pump it a few times before you hear anything. I don't hear it all the time either. Its not a motor that moves because you're braking.

 

Okay...I'll add some research data here.

If the car is in PARK, I cannot get the noise to start, even when pumping and then holding the brakes.

If I roll the drivers side window down and then back up, once the window is rolled back up, the noise goes away within 1/2 a second. The window is up when the noise starts.

This is some weird stuff to me......

 

How the hell did you get the window involved?

Now you're gonna have to really describe the sound to get a good diagnosis 'cause now you threw a weird variable LoL

(and it takes about 4+ pumps to get the sound IF its the booster motor)

 

I'm going to try to video it this weekend. This is wierd.

 

LOL This is too funny.

That's right. My car does exactly the same thing.

It does it consistently, while driving, standing still, in Park, in Drive, etc. The brake booster is just building up pressure again (and when it does that the brake fluid in the reservoir goes down btw).