My Brakes are Barking at Me

<div class='quotetop'>QUOTE(TonyPSchaefer @ May 17 2006, 07:44 PM) [snapback]256982[/snapback]</div>

As long as they don't bite you .......... :lol:

 

Tony, I too remember discussing this issue.
This is happening at a dead stand still??? Not kosher. Is there anyway you can get someone to stand outside the vehicle while it's happening? (Prefferably a Prius tech in a parking lot!). What happens if you let completey off the brakes (car in Park)? Does it stop? I bet it's the brake accumulator pump system. Sometimes hydraulic fluid can squeal as it passes through a restriction (like a valve) and it can change tone as the amount of pressure increases. Try a few stops using only the E-brake and see if it still happens.

 

My car did this at every stop (brake to a stop and then I'd hear a little "toot" like someone just touched the horn) for the first 20-30km after I got it back from the body shop for a rear bumper replacement. They did no work on the hybrid systems or the braking systems at all, they just replaced the bumper and did some frame and body work.

The only other symptom that I noticed was that the 12V battery was very low after sitting in the shop for 2 weeks and drawing a large charge current from the converter, so I suspect the "toot" is likely related to currents in the inverter/converter as it went away after the battery got a decent amount of charge in it.. Have you checked your 12V battery?? Short of taking the battery right out for load testing, I'd suggest a voltage check at the very least and a current check if you can get your hands on one of those clamp-on ammeters..

 

The only time this ever happened to me was during the week that my husband and I were in the mountains on a snowboarding trip. It never happened before then nor since. I wondered if it was the cold temps (15-35 degrees F and very low humidity) and short trips (1/2-2 miles). We would stop at a red light, and then hear the light-horn-honking sound and there were NO other vehicles anywhere near us. It would happen every time I was stopped at a light with my foot on the brake while up there, not just every once in a while. :blink:

 

<div class='quotetop'>QUOTE(TonyPSchaefer @ May 17 2006, 01:44 PM) [snapback]256982[/snapback]</div>

THANK GOD - I'M NOT CRAZY!!!!!!!!!!!!!!!

This same thing happened less than a month after getting the car in Nov. When it was in
for servicing (5,000mile) I asked the dealer to check. They said nothing happened - no
cause.

While it happened for a short while after that, it then has completely stopped making that noise.
Has been quiet now about 3 months.

When it was acting up it would also make noise when I started and put it into park to shut down.

Now I'm not sure whether it was the cold weather or just a "break in" thing. But since your's is
a 2004 I think the "break in" explanation goes out the window.

 

http://techno-fandom.org/~hobbit/cars/brakerust.jpg
.
_H*

 

have still never heard of this...

if anyone around central NC experiences this, DH would love to see what it's about.

 

I just got back from a long road trip (3,000 miles - CA to CO and back, now have over 50,000 miles on the odometer) in my 2004, and it made the same "barking" sounds on three separate occasions during the trip. It even gave me a "pweeee" sound a couple times (think of the noise a balloon makes when you let the air out by pulling at the stem with thumbs and forefingers). I stopped in a Colorado dealership to have them check it out, but by then it wasn't acting up.
Everything seems fine now that I'm back home.
I've made this trip in the Prius before and I don't recall hearing anything out of the ordinary.
I'll just have to keep an eye .... er, an ear on it.
- Ed

 

I get this with increasing frequency proportional to how cold it is. When the car is cold, and the outside temp is cold enough for a snowflake, every deap stop with the foot on the brake produces a little honk. It also happens if I haven't moved at all, but press the brake down firmly. As the car or the air gets warmer, the noise is more seldom heard.

I follow the theory that it has to do with cold temps and low humidity. I'm in Phoenix, so it is pretty much always dry. That might account for some of the difficulty in tracking the issue. Other areas would cycle humidity more and if that's a part of it, the sound would be more transient. Although, TonyP is in Chicago, and if memory serves, its generally humid there.

 

It's been almost two years since I've posted here (I think), but it is good to be back.

I too get the barking from time to time when the car is completely motionless.

I haven't had it in a while, but if I want to try to reproduce the noise I find that if I come to a slow, gradual, and gentle stop when the brakes are cold... And then once stopped... imediatly press firmly on the brake pedal... I can sometimes get the "bark."

Perhaps if you want to attempt to reproduce the noise for a service tech, you can give it a try.

Cheers,

~Andrew

PS
I refer to the condition as "my sea lion."

 

Count me in for wanting to know what the hell this is!

No, Hobbit - NOT a rust problem. Not the surging problem (that I also experience that has nothing to do with brake rust). This is something like "chirp." Tough to describe. No feel of it from the brakes, just the sound. My car just turned 2500 miles, and was up in the mountains in *warm* weather when it started last week. The only thing I'm doing different is taking many very short trips (taking my kayak down to the lake, and then back up again. About one mile each way - always on a cold start). It only happens when I move very slowly (under 5mph, and then apply the brakes). I'm actually rolling when it happens. And it is VERY quick bark. Like 1/4 of a second, and it just barks once per brake application. Happened for five days while I was up there, and then after the drive home today... nothing. All gone. Wth?

It is pretty loud when it happens. NOBODY who's near can miss it. But heck if I can ask the service guys since it doesn't do it now that I'm home.

A Sea Lion bark is a VERY good description!

 

<div class='quotetop'>QUOTE(htmlspinnr @ Jun 27 2006, 08:18 AM) [snapback]277367[/snapback]</div>

Yes, very interesting. I was at 7,000 feet and mid 80's. Maybe an over-pressured brake booster that bleeds off a check valve in these high-altitude/low ambient pressure situations?

Has anybody ever heard it near sea level?

 

Yes,

I have heard it at sea level (approximately 10 feet MSL), which is where I spend most of my time.
Also, I have noticed it from time to time in all four seasons. It doesn't seem to be more frequent at any particular time of the year.

It doesn't happen often, and I'm really not bothered by it. It gives the car character.

~Andrew

 

I too have experienced the phantom "bark".
My wife & I think of it more like a chicken clucking......but sea-lion (moaning for an anchovie)
is probably a more apt description.
We live close to sea level and it's been going on in very hot temperatures (Florida in August).
I thought for a while it was related to the brake discs being wet (as we get lots of rain down here)
but it's happening rain or shine.
My best guess at this point is that it might be binding of the plungers on the front brake calipers.
I've heard of examples in other (non-Prius) vehicles where shops fitted these plungers with a nylon sleeve
to prevent this kind of binding. Don't know if this is, in fact, the source of the bark, but I thought it might be something to consider.
Anyone else have any other ideas?

 

My 2006 with 9100 miles has just begun barking too. It started this weekend as I drove around searching for a good park for a birthday party. I'm at sea level in fairly balmy weather.

I can make mine bark pretty consistently by coming to a slow stop and then pressing the brake pedal all the way down. They also often bark when I shift to reverse or park.

I'll bring it up at my 10K tuneup, but I don't feel confident after the dealer couldn't find out why the MFD fails at high interior temps.

Stealthgirl
2006 Silver Pkg 8