[Quietcars] Toyota admits Prius had brake design

Thu Feb 4 15:45:22 UTC 2010

Hi Michael,

This latest news from Japan of a technical fix is certainly welcome news to 2010 Prius owners. I wanted to share some of what we've found in the Prius community.

In a 30 day poll, about 50% have reported experiencing the brake problem. I'm one who hasn't experienced anything beyond what happens when only two of dozens potholes have been hit lasting only at these two pothole ... not beyond. Of the 50% who reported experiencing the problem, about 20% believe it is severe. These are the owners I've been working with to identify and quantify the problem.

I've collected a series of Google Street View and digital photos of specific locations where this happens. For those who have limited vision, you can find them at:
http://hiwaay.net/~bzwilson/prius/Prius_bump_010.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_020.jpg

Just increase the digits in the image URLs by 010 up to "Prius_bump_200.jpg"

So far, I've tried to recreate the problem with our 2010 Prius and have had no luck. This includes different braking experiments on snow and ice covered back roads as well as trying to hit just about every pothole, railroad crossing and manhole cover I can find. For example, braking with different forces on an icy road with one wheel on snow and ice and the other on pavement. Nothing abnormal happened as traction control came in and I had full steering and ABS let me come to a stop. The car stopped fully under control. Understand I am trying to recreate this problem and I'm not having any luck with our 2010 Prius.

I'm a conservative engineer, which means I'm not ready to try can call a diagnosis. It is still under investigation. However, this is what those who I've been working with have reported:

1) specific road defects - it has been in one case cleared by repaving the road
2) inconsistent - it doesn't always happen but variable, seemingly random times, the first time being a mixture of surprise and alarm
3) harder pedal pressure - the car stops abruptly, by mashing the pedal right away, the car comes to almost an instant stop to extent of surprising passengers
4) slow speeds - 50% report it under 20 mph

The Prius braking system is a fairly complex system including a dedicated computer, multiple hydraulic valves, yaw and accelerometer, brake pedal position sensor, and an active interaction with the transmission. The maintenance manual discusses a fairly involved calibration process to make sure all elements are working together.

There are two other risks, sticking accelerators and even a Steve Woz report about the cruise control. The accelerator problem has two causes, the CTC part that is being modified with a shim in one recall and the earlier problem of floor mats catching accelerators. In both cases, the driver pushes the accelerator to the floor, maximum acceleration, and it doesn't come back. The workaround is to shift into "N" and then use the mechanical parking brake or remaining brake capacity to come to a safe stop. I've practiced both methods and know they work. Furthermore, our 2010 Prius cuts power when the brakes are applied.

As for the Woz report on cruise control, he eventually admitted it was more operator error than anything else. He 'stacks' accelerate commands to the cruise control computer and then the car 'takes off' and he backs them off. He was also trying to make a valid point about difficulty reaching a help desk or complaint center including the NHTSA.

There are a lot of folks willing to spread Fear Uncertainty and Doubt and I'm not here to minimize what appears to be a valid, intermittent, braking problem. The braking problem does exist even if I can't replicate it and it is being addressed. We just don't have a final resolution, yet. I can confirm others have reported credible, symptoms, and I'm working with them to identify where it happens and try and replicate their results.

If you have additional questions, I'll answer with what little I've learned.

Bob Wilson

> Date: Thu, 4 Feb 2010 07:55:27 -0500
> From: mrtownsend at optonline.net
> To: tse-chat at uyahoogroups.com
> Subject: [Quietcars] Toyota admits Prius had brake design
> 
> One more for Toyota.  They have been under the microscope lately, but, I
> think that all auto manufacturers have had their bad streaks of luck.  And,
> because of global input of each manufacturer, for example the CTS
> accelerator pedal assemblies that are universally utilized by each
> man7ufacturer, Toyota may be one of many who will experience the issue of
> unintended acceleration.  This brake software recall message is also one
> which Prius owners should check out thoroughly and act if their VIN number
> is one of those which is being looked into.  
> 
> 
> There have been recalls or technical service bulletins issued on vehicles
> for as long as I can remember, and this recall situation is not unique to
> Toyota. Ford and GM, as well as Chrysler have made cars for years that been
> inferior in design and overall quality, and they have issued recalls for
> engines that self-destructed due to lack of lubrication or cooling.  There
> have been transmission recalls for all manufacturers.  Ford had a large
> issue with cars that were not fitted with a piece of shielding that would
> have prevent cars from exploding if they were rear ended, and the famous
> Ford Explorer/Mercury Mountaineer recall of tires and suspension is one for
> the books as well.   
> 
> All manufacturers have done their part to fix wrongs once they were found
> out by consumers or watchdog organizations.  And, I'm glad for the fact that
> manufacturers and consumer groups work together on these issues.   
> 
> The sad part of this whole recall issue is this, or at least, it's my humble
> opinion of these things.  I think that many people don't want to be bothered
> with bringing their cars in for repair because it takes time away from their
> regular chores to do so, and most often, they don't either have access to a
> rental car or another vehicle to drive, or their communities don't have a
> rental facility available.  Please take advantage of the recalls.  If it
> weren't for consumer organizations and watchdog campaigns, this notification
> process probably would have never been off the ground.  
> 
> Mike and Brent
> 
>   
> 
> Toyota admits Prius had brake design problems Employees at Toyota Motor
> Corp's Tsutsumi plant work at a Prius hybrid assembly line in Toyota,
> central Japan. Toyota said its North American and Japanese dealers had
> received several dozen complaints over what drivers characterised as
> insufficient braking on the new Prius hybrid when driving over bumpy or
> frozen roads.
> REUTERS/Toyota
> Motor Corp/Handout
> Comments (3)
> Yuri Kageyama
> Tokyo - Associated Press
> Published on Thursday, Feb. 04, 2010 3:58AM EST Last updated on Thursday,
> Feb. 04, 2010 4:04AM EST T oyota admitted design problems with the brakes in
> its prized Prius, adding to the catalogue of woes for the world's No. 1 auto
> maker still reeling from a massive U.S.
> recall involving faulty gas pedals.
> Toyota Motor Corp. spokeswoman Ririko Takeuchi said Thursday that Toyota
> discovered there were design problems with the antilock brake system and
> corrected them for Prius models sold since late January, including those
> being shipped overseas.
> But the company said it was still investigating how to inform people who had
> bought the gas-electric hybrid cars. Nothing was decided on that front for
> Prius cars sold overseas, according to Toyota.
> Complaints about braking problems in the third-generation Prius have been
> reported in both the U.S. and Japan, combining to some 180, and come amid a
> global recall of nearly 4.5 million other top-selling vehicles for faulty
> gas pedals.
> "We are investigating whether there are defects in the Prius," Toyota
> executive Hiroyuki Yokoyama told reporters at Toyota's Tokyo headquarters.
> The company gave few details of the brake flaw. A major Toyota dealership in
> Tokyo said the auto maker had informed dealers that Prius brakes can
> sometimes fail to work for less than a second but it had not told owners.
> "It is disappointing because the Prius was receiving such rave reviews,"
> said Hiroyuki Naito, a manager at the dealership. The latest model Prius hit
> showrooms last May.
> The problem with the Prius - the best-selling hybrid in the world and
> Toyota's flagship model - is a big embarrassment for the auto maker in its
> home turf Japan and another blow in the U.S., its biggest market.
> In recent weeks, the auto maker had answered questions about its overseas
> recalls for gas pedals with assurances that problems didn't extend to
> Japanese vehicles, implying that it was doing a better job with quality
> control in Japan.
> The transport minister is ordering an investigation and said a recall for
> the Prius should be considered. U.S. authorities are also investigating.
> Earlier in Washington, U.S. Transportation Secretary Ray LaHood startled the
> public with a comment, which he later retracted, that Americans should park
> their recalled Toyotas unless driving to dealers for accelerator repairs.
> The popular gas-electric Prius was not part of the most recent recall over
> sticking gas pedals in eight top-selling models including the Camry that
> spanned the U.S., Europe and China.
> Toyota senior managing director Takahiro Ijichi defended the automaker's
> quality standards.
> "We have not sacrificed the quality for the sake of saving costs," he said.
> "Quality
> is our lifeline. We want our customers to feel safe and regain their trust
> as soon as possible."
> Toyota for the first time gave an estimate of the costs of the U.S. recall
> at up to $2-billion (U.S.), with $1.1-billion for the costs for the repairs
> and $770-million to $880-million in lost sales.
> The Prius, the world's best-selling hybrid, has been extremely popular in
> Japan because of government incentives that made hybrids tax-free. More than
> 170,000 the new remodelled Prius cars were sold in Japan and about 103,000
> have been sold in the U.S. since May.
> Despite snowballing problems with quality, Toyota said Thursday it returned
> to profit in the October-December quarter because of healthy sales of its
> green models including the Prius, and raised its forecast for the fiscal
> year through March.
> Net profit for October-December was about $1.7-billion. It forecast a
> $880-million annual profit compared with its previous forecast for a
> $2.2-billion loss.
> Toyota also raised its full year sales outlook to 7.18 million units from
> 7.03 million.
> The revised forecast remains lower than the 7.57 million vehicles it sold
> last fiscal year. And it is unclear how well Toyota sales and profits will
> hold up in coming months.
> 
> 
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