Sound when you press brake pedal

I have never heard that sound in my Prius Three model while driving, and braking to a stop.

But I do hear a similar sound one time, when I first get in the car and before I even start moving.

 

if it's the buzz/wirr sound that coast gets when opening the driver door, it's the same thing. the car has to keep replenishing the brake accumulator. keep in mind, it's drive by wire.

 

Yes, that's it bisco. Thanks. I just went out to the car to see if I could hear it again: I pressed the brake pedal, pushed the On/Off button, and then I heard it about 4 seconds later. It's a quiet buzz.

Then I released the brake pedal, waited a couple seconds, then pressed the pedal again, and the buzz/whir sounded. ( But I never actually notice it when I'm driving. Too much other noise I guess.)

I will add this to my growing list of Interesting Prius Oddities.

 

agreed, it's not as noticeable when driving, except under the right circumstances, but it's an ongoing process of depletion and replenishment.

 

bisco, can you explain please what that means?

"I'm sorry, dear, I can't make our date tonight... I have to go replenish my brake accumulator."

 

Very interesting! What is actually being depleted/replenished? Electricity storage for the brake system?

 

prius has a non direct braking system. you step on the pedal, but it doesn't squirt brake fluid through the brake booster and out to the calipers. it 's just a sending unit to the ecu, telling it how hard you're pushing, and how much brake force to apply. the accumulator is the power source for the hydraulic fluid.

that's why there was so much controversy about unintended acceleration, the software does the braking, not you. there is a manual hydraulic override if you push hard enough though.

good question on what is being replenished. i want to say brake fluid under pressure? maybe air, idk.
i just know it makes a noise.

 

Well, I'm enjoying all the Star Wars sounds. It's interesting hearing all that technology at work. (But those giant ants kind of concern me. )

 

Yeah, I just drove about 30 miles and I never heard it. (Only the one time when I first got in the car.) Even the giant ants were quiet today when I drove thru McDonald's for coffee. And even my Toyo Tires seemed quieter this morning..... What the heck is going on!!??

And, the display is showing that I'm getting 65 miles per gallon (all in town) after 360 miles driven, and 100% in the PWR mode! Something is really fishy....

 

In a normal car, the engine running all the time creates a vacuum, which is used to power the brake booster pump. In a prius, the engine isn't running all the time, so they use an electric motor to provide the power to the brake booster. (I think...)

 

Old age sir, turn your hearing aid up, the batteries are dying, and go see the optician about that 65 that's appearing on your glasses, it might be the prescription strength.

 

I heard it several times this morning.

"May The Force Be With You."