Weird sound while braking

That mechanic has one of those toyota scantools right? Otherwise he may not have correctly bleed the brakes.

Anyway, if it sounds like a buzzer of sorts, then thats the brake accumulator pump - which runs approx once every 3 brake pedal pushes.

 

Hi welcome!

Since you have had the car for 2 years you are probably aware of the brake vacuum motor that turns on freq. when you apply the brakes. Sort of a soft rattle-rattle-rattle from under the hood and kind of behind the dash? You can replicate this noise by activating the brake vac motor by pressing on the brake pedal a few times at a stop light.
If its not that its a mechaniical issue. You did not post how many miles on the car. and or if its the front brakes or the rear brakes
that are making the noise.

If the fronts be aware they have no "springs" and also be aware not to many mechanics can drain the "ABS" brake fluid on our cars. I have an 07 also. You said "mechanic" so I assume its not the dealer. Its a very special process bleeding the brakes on our cars and requires special Toyota software to perform. It is out of reach for most mechanics and if he did open the brake fluid system on your car you need to take it to the dealer for a check. Thats a big safety issue there. Unless he just outright lied to you which I suspect because if he did he would not be able to bleed your brakes without the laptop software. And if you took it to the dealer I can't think why they would drain out the fluid.
Anyway you might just need a standard brake shoe job. But most of our cars do not require that until at least 100K plus miles as the brakes are very gently used because of the braking assist of the regenerative braking system. Now having said all this sometimes the brake rotors just need to be cleaned. Easiest way to do that is to get up to speed...slap the gear shift into neutral (which releases the electronic brake regen so now your on mechanical brakes only !!!) and apply firm brake pressure. Do this a few times. Don't lock em' up just apply firm pedal at say 50 miles an hour. I do it all the time. You can tell by looking at the disc's through the wheel slots up front and see how rusted the rotor disc is.When they get real rusted time to clean them.

Please post back on how many miles...front or back sounds....or if you took it to the dealer and not a regular mechanic.

 

There is no vacuum pump, it is a hydraulic pump pumping into an accumulator.

 

Check out this thread. It might relate to what you describe:

http://priuschat.com/forums/gen-ii-prius-technical-discussion/19051-my-brakes-barking-me.html

 

The fix for this noise would be replacement of the brake actuator/ accumulator and resistor per TSB. If you're out of warranty the part is roughly $1600 and requires 4.4 hours of labor to install and bleed the brake system. At our dealer this is a $2200 repair. The noise does not effect brake system performance by any means. All replacement does is get rid of the noise, which, yes, is annoying. This is covered under your 3yr/36,000 mile waranty.

 

You're welcome. Hope it was helpful. It was the first thread I thought of when I read your post.

Connie

 

Hi gents.
I am facing same er er sound in my Prius Alpha as Sharon explained. No any brake or warning signs appear on dashboard. Viered sounds feel at padal and it's surrounding. While braking at 50km ABS starts soon after braking and feel that vehicle is sliding slightly and this gives me feeling that my car brakes are week.
My vehicle current driven km is 150K.

Please suggest and advise