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Toyota Prius Brake Problems

366 messages,  Last post on Mar 27, 2013 at 6:44 AM

You are in the Toyota Prius Maintenance & Repair Forum.

What is this discussion about? Toyota Prius, Brakes, Hatchback, Sedan

    
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Messages Page 22 of 37

#207 of 366 Re: STILL CONFUSED Re: Spoiled Food for Thought [masterpanda] by hal_cat

Feb 28, 2010 (11:21 am)

Replying to: masterpanda (Feb 28, 2010 9:44 am)
I called my dealer and got an appointment the same day - my computer has now been reflashed. Motivation? After feeling the symptoms just once since I got the car last August, this past Friday I felt it twice. I wish I could feel complete confidence in the upgrade, since I know that most software is not written from scratch but modified from previous versions, and I am convinced that eventually Toyota will need to fix the problem with the previous brake software in the 2005-2009 cars. Will that problem still be in my Prius?

#208 of 366 Re: STILL CONFUSED Re: Spoiled Food for Thought [masterpanda] by wwest

Mar 01, 2010 (11:16 am)

Replying to: masterpanda (Feb 28, 2010 9:44 am)
Your Prius, any Toyota, or Toyota "like" HSD systems have BTO by default. When you apply the brakes the HSD firmware is designed to enter regen mode. It is not possible to have regen active AND simultaneously DRIVE the wheels. Well, maybe the F/awd RXh or HH with 2 "drive" channels.
 
While it is possible to specify firmware operation that would give priority to the gas pedal position over regen braking that is NOT very probable. That would not only be a serious flaw in the design but would border on intentional, criminal, action.

#209 of 366 Re: Spoiled Food for Thought [bwilson4web] by 07prius

Mar 01, 2010 (11:44 am)

Replying to: bwilson4web (Feb 27, 2010 11:26 pm)
bwilson4web: Why does your point have to be made in such a disrespectful way? My goodness, would you speak to me this way if we were talking in person? Right or wrong, I have been very respectful in my posts and expect the same in return. I am not betting my credibility on the review I posted...which is why I called it "food for thought" as opposed to "hard facts." What I experienced is real; I only said "40 feet" in my OP as a gross estimate; in truth I may have been further away, but I cannot be sure, which is why I said from the get-go that I wasn't making a claim that I was not at fault. The '82 MBZ 240D I drove for the past few years had quite a long stopping distance, but I knew what to expect, and never rear-ended anyone in it. I did not realize that the post would be dissected and discredited right out of the gate. I guess I am the kind of person who tries to fully understand someone's point of view before seeking to invalidate it.
 
Thank you to those who are respectful on this and any forum.

#210 of 366 Re: Spoiled Food for Thought [07prius] by bwilson4web

Mar 01, 2010 (3:46 pm)

Replying to: 07prius (Mar 01, 2010 11:44 am)
Look, I'm sorry that it came across so harsh but it has to do with citing credible sources. Our local newspaper has a letters to the editor section and every now and then "people not in touch with reality" post complete nonsense. If I were to cite their letter as a source, any and everyone would be right to condemn me for introducing a bad source. Remember, even fibbers can post.
 
If you go back to that original source, you'll notice I replied with the actual ratio of Prius and Corollas for those model years and the ratio is ~2.6 to 1, not the '5 to 1' ratio used in his numbers. If he can't get the ratio of cars in that model year right, how are we to trust his other numbers?
 
Understand he may be right about the counts of "reports" but look at his own numbers:
 
44 - Prius
7 - Corolla
 
The problem is 7 is not statistically significant. It is too small to draw any useful conclusions. So his ratio itself is suspect, as well as his counting.
 
I won't complain if you 'do the math' other than if I follow the same procedure we come up with different numbers. Then we'll discuss methodology and make sure we are seeing the same data. But as it stands, that source suffers from a major self-evident problem and a factually inaccurate count of vehicles.
 
The reason I knew the vehicle count is I've been looking at the Toyota December sales reports for the past couple of years. This has the total number of Prius and Corollas sold:
http://pressroom.toyota.com/pr/tms/toyota-reports-december-and-2009-150487.aspx
 
Bob Wilson

#211 of 366 NHW11 vs NHW20 vs ZVW30 brakes by bwilson4web

Mar 01, 2010 (5:23 pm)

Hi,
 
The ZVW30 Prius, 2010-current, has the redesigned brake system and the recent recall to get rid of a rare, brake pause. The NHW20, 2004-09, has not been recalled but there are reports that it has a similar but less severe pause. The NHW11, 2001-03, is my commuting car and none of my tests have replicated the brake pause.
 
2010-current Prius - SSC-A0B
 
You don't have to wait on a letter or call from the dealer. Call your local Toyota Service Center and schedule an appointment. If the service writer gives you any grief, ask to speak to their manager ... keep going until you get the right answer, "Yes, come in and we'll fix it." Alternatively, call another Toyota dealer or ask them if you should call the local newspaper.
 
The problem is rare and intermittent. Probably the surprise, more than anything else, catches folks off guard. Just press harder on the brake and the car stops almost instantly. In the meanwhile, keep your following distance on the long.
 
2004-09 Prius
 
There are reports but sad to say, I'm not having much luck documenting the pause. I have an accelerometer that clearly showed the ZVW30 brake pause but I've yet to find someone with a NHW20 to test. I may have to rent one.
 
We have a poll going on in PriusChat about the brakes and the numbers are:
 
55 - Yes, I want it fixed (22%)
41 - Yes, However it doesn't bother me (16%)
153 - No, I don't feel my GEN II Prius has a problem (61%)
 
So over half don't see a problem. Only 22%, 1 in 4, wants a fix.
 
2001-03 Prius
 
I have one and following the same protocol as our ZVW30, I can't find any pause in the braking using the accelerometer.
 
Bob Wilson

#212 of 366 Re: NHW11 vs NHW20 vs ZVW30 brakes [bwilson4web] by sthoge

Mar 02, 2010 (1:42 pm)

Replying to: bwilson4web (Mar 01, 2010 5:23 pm)
Bob,
 
Perhaps you could post your general area and someone that lives near you could volunteer.
 
I have a 08 Prius and I have experienced the the momentary release of the brakes when hitting a pothole or rough road, but immediately after the brakes grab. I have even hit areas of ice and the ABS has always kicked and assisted in a timely stop. So over all I am more than happy with the performance of the braking system. Although I wouldn't complain if they removed or shortened the momentary release when you hit a pothole.

#213 of 366 Re: NHW11 vs NHW20 vs ZVW30 brakes [sthoge] by jacquesc

Mar 02, 2010 (2:39 pm)

Replying to: sthoge (Mar 02, 2010 1:42 pm)
I'm not saying you are not being truthful - however, I am saying you must have not take all situations into consideration. If you were behind someone at a safe distance and they slammed on the brakes for whatever reason. Then, you attempt an emergency stop and a bump in the road causes a couple seconds of complete loss of braking... almost guaranteed an accident will occur. The next step (after making sure that everyone is ok) is deciding who's then who is at fault?
 
I stand by my prior accusations that the poor engineering of the car is the reason for the accident. Thus, Toyota is at fault for not addressing the problem in the 2nd & 3rd generation Prius.

#214 of 366 Re: NHW11 vs NHW20 vs ZVW30 brakes [sthoge] by bwilson4web

Mar 02, 2010 (9:42 pm)

Replying to: sthoge (Mar 02, 2010 1:42 pm)
You wrote:
 
"Perhaps you could post your general area and someone that lives near you could volunteer."
 
I'm in Huntsville AL and had one possible volunteer but he never followed up. So I'm thinking rental car. But I'll need a rainy day for the test.
 
The other option is the iPhone and iPod Touch have a built-in accelerator chip. I have no fiscal interest in them but there are at least two applications that record accelerations fast enough to gather engineering data over short intervals. Dynolicious Logger is one I've tested and within short intervals, 30-45 seconds, the data is usable. Unfortunately, I'm see long term drift that limits it to mostly short tests like the brake pause.
 
Bob Wilson

#215 of 366 Prius 2010 Brake fix by whitecliff

Mar 04, 2010 (4:51 pm)

Well it happened again yesterday. Fourth time on my new (January '10) Prius.
I was slowing for a turn, going about 18mph and the car surged ahead.
I thought there was a recall but I still haven't heard anything from them yet.
Does anyone know if the "flash" worked?

#216 of 366 Prius brake recall by masterpanda

Mar 04, 2010 (6:39 pm)

If your car was made in the last week of January, it already has the post-recall brake configuration; your dealer will know. Mine, bought Decemer 12 needed the fix and I got it February 15 in a one-hour visit to the dealer. I still have not received paperwork from Toyota Motor Sales USA about the recall, but I did get an email about it from the dealer about a month ago and I immediately made an appointment. The problem it fixes, disconnection of the ABS momentarily when you hit a bump or one or both traction wheels lose road contact, is something I experienced early and got used to. I did not really need the recall because I knew my brake was always operative and I use it automatically in those situations, with no need for ABS support. A couple of times the ABS activated on snow, and I did not like it all, and it did not help (I did not expect it to).
On the "other" brake issue, my dealer told me in a phone call yesterday that all Toyota hybrids " already have brake override." I think that is not the correct use of the term, because what the service department told me was that the brake pedal always "has precedence" if both accelerator and brake are pushed simultaneously. I think true brake override would mean the engine shifts to neutral when both pedals are pushed, with no need to touch the shift. The dealer is mailing me a 16-page hardcopy explanation of how the Prius brakes work; she said it was technical, but I am very interested in reading it. As far as I know, it is not available on the Web, but your dealer might have it.

Messages Page 22 of 37

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