2020 4Runner brake pedal making an electro-mechanical sound when depressing the brake

[Charles Bronson]

All of a sudden my wife's 2020 4Runner started making an electro-mechanical sound when depressing the brake pedal. When parked, I can get it to make the sound on the second full brake pedal depress. When the sound occurs, you can also feel a slight vibration in the brake pedal. It's rather annoying. The video below was taken from a 2021 Tacoma. This is the exact sound we're hearing (and feeling).

Between December/January of last year, we dealt with quite the fiasco of a failed ABS brake booster assembly. It Toyota 6 weeks to get it completely sorted because they didn't program the brake system correctly thus made the truck incredibly dangerous under moderate/heavy braking (back axle would lock up and the truck dart hard to the right). We're really not looking forward to re-visting this problem again.

<iframe width="560" height="315" src="https://www.youtube.com/embed/b3NDWGJM5Rs" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>

 

[Whippersnapper02]

Not sure how much power assistance is available in the reservoir but eventually the system will have to pressurize itself again which is why the pump turns on. Mine will do that with enough pumps of the pedal.

 

[Charles Bronson]

Not sure how much power assistance is available in the reservoir but eventually the system will have to pressurize itself again which is why the pump turns on. Mine will do that with enough pumps of the pedal.

Thanks. So you hear and feel the exact sound?

We've always heard the Toyota "pssshhhhh" sound when depressing the brakes, but this electro-mechanical sound (does sound like an air compressor in the distance) and vibration through the pedal is new. Even my wife, a non-car person, noted it to me.

 

[Whippersnapper02]

Thanks. So you hear and feel the exact sound?

We've always heard the Toyota "pssshhhhh" sound when depressing the brakes, but this electro-mechanical sound (does sound like an air compressor in the distance) and vibration through the pedal is new. Even my wife, a non-car person, noted it to me.

Same noise. I can get a video of it at some point.

 

[tpete]

Do you notice the amp meter fluctuate when the sound is made? That would be the booster repressurizing. Mine makes that same electro mechanical sound when: shutting the door and first starting the engine; a slight sound about 15 ft after first moving forward; and then when I park, turn off the engine, and as soon as I open the driver's door. It's always made these sounds, but my booster cycles about every 8 seconds very quick and has been doing that for about 1 year now.