ahc21ahc

I just got an 07 GX and noticed a vibration in the brake pedal. The easiest way to reproduce it is to have the car on and in park. Depress the brake pedal all the way down once and hold for a second or two. Release. Then depress all the way down again and hold for up to three seconds. Repeat until you feel 2-3 seconds of vibration in the pedal. It should happen every other time you depress the brake pedal. Only the pedal vibrates, no other part of the car vibrates.

I initially noticed this vibration when coming to a stop from slow speed. It is easy to reproduce if you step on the brakes very lightly - only about 1/4 or 1/5 of the way down. You have to step on the brakes lightly a few times for the vibration to show up.

This annoyed me so much I brought it into the dealer to have it checked out. They said this is normal for a GX and a few other Lexus. I tried to reproduce this vibration on a brand new 07 GX they had on the lot and got a simliar vibration, though this one was a more abrupt vibration, but lasts less than a second.

Anyone else notice this? There is a TSB out for 02-04 Camry with a similar problem. Here is the text of intro to the TSB:

In some cases, the customer may feel slight vibration in the brake pedal during initial
pedal stroke. The vehicle does not have to be in motion to feel the vibration. A new brake
master cylinder service part was developed to address this slight vibration concern.

ahc21ahc

Can someone please let me know if they feel this vibration in their brakes as well? Thanks.

The G Man

No vibration here.

ahc21ahc

It appears that quite a few 4runner owners have experience this problem

http://www.toyota-4runner.org/showth...=&threadid=884

http://www.toyota-4runner.org/showth...threadid=18975

What should I say to my dealer to have them replace the master cylinder? They claim the vibration is normal.

V8_Fan

Yeah, I heard about the complaints about that "tapping" feel on the brake pedal in the 4runner forum. I also heard there were enough complaints that Toyota eliminated that "feature" on future vehicles. Apparently, it's by design. My folks' '03 camry does the same thing, bugs me when I drive it (not to mention the extra long stroke in the brake pedal). Toyota claims it's a "two-stage" booster, but in reality, it seems on only brake when the pedal is depressed way down. LX never had the problem (guess it's too old of a design for toyota to "improve" the master/booster design:-))

ahc21ahc

It's not a "tapping" feeling. It's more of a buzzing/vibration, like a motor is running for a few seconds. As I said, the 02-04 Camry has a TSB to replace the master cylinder due to this exact problem. I'm not sure what to do with my GX at this point. It's an 07 and only 2 weeks old!

V8_Fan

When you turn the ignition only on, the booster motor runs for maybe 30 sec to build up pressure in the brake system. Is this the same sound?

ahc21ahc

Yes, I believe it is the same sound as when the ignition is turned on.

V8_Fan

If so, maybe the master is loosing pressure so the pump is operating to maintain pressure? My LX master does not do this, and it's basically the same electronic type as on the GX.

lexite

I have the exact same symptom. I get that motor sound when I press brake pedal, not every time but very frequently. Didn't know it is a problem... thought it was normal. I'll have the tech check it out next time.

ahc21ahc

lexite - can you try depressing the brake pedal all the way down a few times while the car is on and in park. You should feel the vibration almost every other time you press down on the pedal (hold it down for a few seconds). I feel it every other time I depress the pedal. It's not obvious when you drive the car, but when you sit there in park and press on the brake a few times, you will definitely feel it.

GGGXXX

Read the manual, it states the pedal will vibrate and that is normal - - too lazy right now to go to the garage and get the exact page number. I have a loaded '06 GX (with KDSS) which also makes enough robotic noises to make you think..but the Manual does a good job of listing what is normal....