Winding Sound from Dash/Steering

It's the brake accumulator pump. The sound is completely normal.

Tom

 

<div class='quotetop'>QUOTE(valleyvillage @ Sep 5 2007, 03:43 PM) [snapback]507547[/snapback]</div>

what is a "brake accumulator pump"? I have this sound too, and it also is loud some days and not others. Of course it was NOT loud during my test drive but was 3 days later! Why does it vary from loud to quiet and back again? :huh:

Thanks
Peggy

 

<div class='quotetop'>QUOTE(fernsmom @ Sep 5 2007, 07:01 PM) [snapback]507563[/snapback]</div>

Power brakes on a normal car use vacuum from the engine to boost the braking force. With the Prius, the engine is not always on, so you can't use it to power the brakes. Instead, the Prius uses a small electric motor to power a pump that builds pressure for the brakes, which is stored in an accumulator (really just a small pressure tank). Every time you press the brake pedal, it uses some of this stored pressure. When it gets low enough, the brake accumulator pump kicks on the build it up again. It kicks on about every third time you press the brake pedal, depending on how hard your press and some other factors. I suspect the difference in loudness is mostly one of perception: when everything else is quiet the pump sounds louder.

Tom

 

That sounds like the noise I started hearing when my battery was really low...I left it at a store to get tint and when I picked it up it had one purple bar... I immed. heard it upon take off mild acceleration..its like a relay buzzing right under the dash in front of the steering wheel or maybe in the engine compartment..I'm thinking now it was the inverter which is directly in front of the wheel on top of the motor. Quite loud buzzing. It stopped after I achieved all green bars after a long drive. Don't let the battery go dead!!!

 

I've kind os suspected that it actually from the motors being in the generator mode. The windings in the motors can also create a similar sound. I've kind of coorelated the sound with the generator mode.

Just my 2 cents.

 

<div class='quotetop'>QUOTE(dhancock @ Sep 6 2007, 11:28 AM) [snapback]507934[/snapback]</div>

There are many funny noises in the Prius. The buzzing one associated with pushing the brake pedal is the brake accumulator pump. Regen braking produces more of a whining sound, much like the traction motor on a subway train or electric bus. The regen whine continues for the entire time, whereas the accumulator pump runs for just a few seconds. The inverter drive for the motors also produces a whine, but it is quieter and higher pitched. It drives some dogs nuts.

Tom

 

In general, the Prius is going to make a lot of strange sounds to a new user. After you own it a while, you don't notice it as much.

 

I'm amazed to hear so many say Pirus noises are normal. I've had mine for 7 years and it just now started making a winding noise, in the past few days, and I've got over 80k miles on her.