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Discussion Starter · #1 ·
My 2005 Prius has 1,750 miles on it. I've noticed a noise, which I think is only a few weeks old, and wanted to see if anyone can corroborate. It seems to come when accelerrating (in ICE) and when slowing down and braking. It lasts only about 3 seconds and sounds like it's right behind the dashboard. It's on the high end of the scale. It's not quite a whirring, not quite a rattle, but not a smooth sound. Doesn't seem to make a difference if the car is warmed up or not. Nothing seems to be affected otherwise, but I hate having an errant sound—especially when I'm trying to show off the car!

Any thoughts?

David
 

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If you have no warning lights you can consider it a normal operating sound. A brake pump operating for more than several seconds would give you a brake light as the accumulator would not be doing it's job. However, good luck on your attempt to identify it for your own piece of mind. I've given up and just expect what I get, after a year and 10,000 trouble free miles with a LOT of unexplained sounds.
 

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Discussion Starter · #4 ·
re: sound

Yeah, there's definitely no warning lights of any kind. It bugs me because I'm quite sure it wasn't there before. Anyhow, maybe I'll have someone at the dealership hear it (assuming it makes the sound when I'm there, which is never a sure bet!).

Thanks for the input!
 

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That is so weird!

I have a month-old 2005 Prius and I started hearing the same strange sound coming from the exact same place about 3 days ago. I've so far driven abotu 1,300 miles.

Another thing I noticed is that ever since this noise started, I get on average 5 MPG less...

Coincidence?

I'd like to hear what your dealership has to say about this... I am bringing mine in on Monday.
 

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Discussion Starter · #6 ·
re: sound

Interesting. Please post the results of your visit to the dealership.
Good luck!

David
 

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see if you can find another Prius owner near you who doesn't have this problem on their Prius. Then do a car-swap (take each other out for a test ride). (To me it sounds like you're hearing the electric motor.) It could be that the sound has always been there, but once you notice it you can never again not notice it. (The only analogy that comes to mind at the moment is cue marks on movies.)
 

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mrv said:
The only analogy that comes to mind at the moment is cue marks on movies.)
Cue marks? I've never noticed those.
 

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Sanny said:
mrv said:
The only analogy that comes to mind at the moment is cue marks on movies.)
Cue marks? I've never noticed those.
If I tell you how to look for/notice them, you'll never be able to watch a movie at theater again. Take it from a once-licensed projectionist - it'll ruin your movie experience, and anyone who goes to the theater with you (as you keep yelling "Cue!" for no good reason every 20min or so...)
 

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Discussion Starter · #11 ·
re: sound

I really don't think it's the electric motor. Especially because the sound is inconsistant. It's an intrusive sound that, again, lasts only for a couple of seconds on initial accelleration and on braking. Also, it doesn't matter whether the AC is on or off.
 

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I'd almost bet money that you are hearing the normal functioning of the braking system. You are going to be in a position to hear brake system noise when you are stopping or when you are letting your foot off the brake. I also hear accumulator purging noises frequently when I'm out of my car and it has been off for a few seconds. Usually by the time I get to the door from my garage into my house. Accumulator purge noise is a whooshing sound, associated with a number of clicks and pops. Brake system noises include a staccato pump like noise that lasts about 2 or 3 seconds.
 

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If it is a high pitched whine or whistle, that's the inverter's transistors oscillating. Quite normal.
Occurs during acceleration as you push lots of current through them to move the motors, and occurs on deceleration as you regen. Lots of current there too.
 

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The sound that I hear after I turn the car off, I assume the "accumulator" sound, matches the description of hte original poster's noise, but not the timing. I don't get clicks and pops and whooshes, but more of a whirr.... that system doesn't operate when the car is running, does it?
 
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