Hey, what was the outcome of having that part replaced? I have a 2006 Civic Hybrid and have the same brake noise, of which my dealership also said that it was "normal". Even though their Sr. Technician took a test drive with me and said, "Wow, that's weird. I've never heard that noise before." I opened a case with Honda Customer Service and apparently a Regional Manager will be contacting me to determine next steps, if any.
Here are some sites that document the same issue:
http://www.carcomplaints.com/Honda/C...003/tsbs.shtml
http://www.hybridcars.com/forums/200...rid-t883.html?
I'd love to hear if anyone was able to find a solution to support my case.
Thanks!
-Robert

 

Hi Robert,

I, too, have opened a Techline ticket but after two visits the dealer and Honda Customer Service still report this is a "normal" noise for my '07 HCH. They have welcomed me to bring my car back so the service manager can hear it, too, which won't be hard because at 3M+ the "flatulence" is increasing in frequency - now several times a day.

My daughter took her driver's test Thursday and upon the second occurrence of the noise she explained to the examiner, "That's the car." He said, "Oh, it's the car..." She passed despite that "passing" embarrassment.

It seems to happen more after we've driven a few miles - I don't hear it immediately upon startup. Sometimes I also hear a little rattle, especially if I need to brake quickly although not in circumstances that the ABS would typically activate.

Thanks, Nancy

 

This has just started happening in my car. It has been about 5 months since I got it. It was happening in stop and go traffic, when I had to step on the gas harder than usual. Other than that one day, it hasn't occurred.

 

There has been a lot of discussion about the strange "squeak" or "farting" that many HCHII drivers have
noticed on some occasions when applying their brakes. The sound appears to come from the brake pedal area or
somewhere just forward of the firewall. Most everyone describes the same sound and so whether it turns out
to be an "artifact of design" (my term for an undesirable element of a properly functioning system) or a
defect, most of us agree that it is obvious and strange --if not humorous, depending on the timing. The
sound does not occur every time the brakes are applied --just under certain conditions that many folks have
tried to predict and duplicate in order to find the common mode that creates it. My '07 exhibits the noise
on occasion, usually during quick brake pedal applications.

One thing is for sure, neither HCHII owners nor the dealers have been successful at fully explaining the
noise. Owners maintain that Hondas don't make strange noises and therefore the noise is the sign of a
defect; dealers and field reps maintain that the brake system is functioning normally. Few dealers or field
reps have offered satisfactory technical explanations for the noise and therefore many people believe Honda
is trying to brush the problem under the rug. Based on my research into the HCHII factory service manual
(which offers detailed insight into the sophistication of the HCHII systems), I offer my assessment of the
cause of the noise and why it continues to perplex owners.

First, let's admit that most HCHII owners have very high expectations for the quality and sophistication of
their vehicles. That's the reputation Honda has built and they execute it consistently throughout all of
their products. Hondas aren't supposed to make "unconventional" noises. However, the introduction of new
technology requires both manufacturers and customers to recalibrate their expectations, and, in many cases,
adjust to advanced products that may not perform exactly the same way as older generations of similar
technology. Case-in-point: hybrids vs. conventional. Hybrids that emphasize fuel economy have required
owners to adjust to a new driving experience, albeit with many desirable advantages over conventional
vehicles.

So, what about the HCHII brakes? Well, you should know that the HCHII brake system is anything but
conventional in design and complexity. Its unique design is required by the fact that the brakes must
transition between IMA re-generation mode and friction brakes as seamlessly as possible. This would be
impossible with conventional brakes only. To accomplish this, the HCHII has an electric power assist system
instead of the conventional vacuum assist found in most vehicles. Remember, a conventional car's vacuum boost
system requires that the engine be running all the time in order to provide power braking --this contradicts
the hybrid philosophy where the engine may be "off" during certain driving conditions or at a full stop. So
Honda applies an electric power booster, instead. There's also a Creep Aid system that keeps the HCHII
brakes applied during Auto-Stop (required by the CVT). Add to this what Honda calls the Advanced Hydraulic
Booster and a system that monitors your brake pedal application pressure and stroke distance, tie it all
together with an electronic control module, add ABS, and well, you get the picture.

So, here are the components of a typical car's braking system:

1. Conventional master cylinder with vacuum assist from the engine
2. Anti-lock braking (ABS) --if so optioned

However, the HCHII Advanced Hydraulic Booster components include:

1. Electric servo motor controlled master cylinder with four solenoid valves
2. Three independent pressure sensors to monitor various braking phases and pressures
2. Power unit (accumulator) with motor (to supply high pressure fluid to the master cylinder)
3. Brake pedal stroke sensor
4. Electronic control module
5. Anti-lock braking system

Here are some interesting excerpts from the HCHII Factory Service Manual:

"The [Honda] Advanced Hydraulic Booster System has a quick-reacting servo unit and a power unit functioning
as a brake booster. This makes it possible to stabilize the braking power while the auto idle stop is
operating. This system can raise the brake fluid pressure control quickly and works in conjunction with the
other systems. The Creep Aid System (CAS) keeps the brakes applied when CVT control requires it during auto
idle stop. This prevents the vehicle from rolling forward or backward while the driver releases the brake
pedal (to press the accelerator pedal) and the engine starts. When CVT control requires the CAS function,
the servo unit operates the solenoid valves [in the master cylinder] to maintain brake fluid pressure. The
brake fluid pressure is reduced gradually while the solenoid valves in the servo unit are operating. When
the driver decelerates or stops by pressing the brake pedal, the servo unit communicates with the powertrain
control module to control the balance between the regenerative control and the normal brake system. In this
case, the brake pedal reaction force is the same as a conventional brake system and the driver is unaware of
the [operation of the servo-controlled brake system]. When the driver does emergency braking, the servo unit
senses the quick rise in the brake pressure. In this case, the servo unit adds pressure to the [master
cylinder] and assists the brake pedal application for the driver."

So, what does this have to do with the brake noise? Well, after many miles and observations I believe that
the momentary "noise" is created when the master cylinder electric servo intervenes with the driver's brake
pedal force to enhance braking pressure (especially noticeable during quick pedal applications or sudden
braking). The "noise" is the brief activation of the solenoids in the master cylinder as high pressure fluid
from the accumulator is applied to the master cylinder to provide additional braking power. Whether or not
the system needs this additional pressure is determined by various brake system sensors at the moment of
pedal application by the driver. It is a normal system function under certain braking conditions and I believe
that Honda will continue to maintain that it is "normal". For sure, there are no brake system failures associated
with the existence of this noise.

Now, the fact that some owners find the noise intrusive in an otherwise composed vehicle is another story.
Can Honda solve the problem? Certainly, and it will probably be addressed in future vehicles. Does it
require that Honda voluntarily retrofit all HCHII's with a new, noise-free system? No, but if Honda had a
quick "band-aid" fix to reduce or eliminate the noise then you would have probably seen it by now. If the
noise is an artifact of the brake system design philosophy on the HCHII, then we, as owners, may need to be
content that we are early adopters of near-perfect, if not fully perfect, technology.

I, for one, am fully content to be driving a vehicle that represents the first revolutionary change in
gas-powered vehicles since their invention. Hybrids are not minor modifications to existing vehicles --they
are the extraordinary results of dedicated research and development to advance fuel economy and lower
emissions with advanced technology that mimics the "conventional" driving experience. For the most part,
everything else on the road, from Hummer to S-class, is still a Model T.

 

Wow Chris. Excellent write up! I think it answered a lot of our questions.

 

Hey Guys, Newbie Here- I Have A 2003 Civic Sport 1.7l Engine (not A Hybrid) With The Same Brake Problem. About Two Years Ago, While Under Warranty I Took It Back To The Dealer For Repair And They Changed Some Brake Parts, I'm Not Sure What It Is, But The Noise Went Away, Until Recently It Start Doing It Again .

 

It does not seem to effect anything, so why worry about it? H

 

well....because when I'm on a date with a hottie, and my car makes a farting noise and in turn my hot date thinks I'm being rude, that would give me reason to worry.

The bottom line is a car brake pedal should not make flatulant noises. If it's due to poor engineering, then Honda should provide a work-around to this rather embarrassing noise while having guests in your car.

For an item that costs tens of thousands of dollars to own (car in this case), I would expect such rudimentary problems such as farting noises from brake pedals to be debugged and fixed.

 

Yes my car honk/farts at me too when I apply the brake, sometimes.

 

I don't think I've owned a car that didn't make a noise when i applied the brakes...the GM cars all had a creak, the Fords and Audi wooshed, all 3 Miatas popped...

The HCH does win the prize for the most random repertoire of sounds however