Recall for brakes DID NOT fix the problem

Thanks, you may have given an important clue.

You are describing loss of road traction, which triggers the ABS. Is this what people are describing:

Look at the apparent loss of braking force in the middle of the ABS event at seconds 257. Is this what folks are reporting?

There is no braking force "in air" or when wheels are so lightly loaded that they have no traction. This is how anti-lock brakes work along with traction control to prevent skidding.

Is this what is being described as "300 milliseconds?"

Bob Wilson

 

Pulling down a largish batch of NHTSA/ODI reports and reading
between the lines turns up quite the array of professional whiners
who clearly don't want to take any responsibility for themselves.
Hopefully nobody here on PC falls into such a category.
.
_H*

 

There's some interesting logic.

You feel it's unsafe - so you continue to drive it risking not just yourself but eveyone else on the road?

THAT DOES NOT HAVE THE RING OF TRUTH, SIR!



-Brad

 

You have more patience than me. I find the raw reports nearly useless because there is no effective way to ask follow-up questions.

When the problem was first reported, roughly 1/3 to 1/4th stayed around and only a small number of good people shared details and answered questions. There was a brake pause that SSC-A0B corrected. But these latest brake problem reports are thin:

• Those announcing they sold their Prius - again and again and again. I wish they'd go find another, non-Prius forum, who awaits with baited breath their reports.
• Those who don't let anyone else drive their dangerous Prius - sounds like a clever ploy to monopolize the car . . . I wonder if it works.
• Those who complain without when, where and how - too lazy to provide facts and data, they have plenty of energy to complain.

If someone has a problem and wants to fix it, I'm with them every step of the way. But these latest reports sure act like they are protecting 'the problem' from resolution. They act as if they don't want it diagnosed and fixed . . . pathetic.

I'll monitor the brake threads for another week but I have better things to do with my time. All it takes is:

1. Where in a Google Map description did it or does it occur?
2. What were the weather conditions?
3. Do you have or can you get a photo of the area?
4. What speed and direction?

These questions separate the goats of the angels. The more one complains without details, the more it looks like a 'time waster' who needs to go on my "Ignore User" list. Life is to short to spend time with b*llsh*t . . . answer the questions or visit the <TBD_car> forum for sympathy and attention.

Bob Wilson

 

1. Google earth 49.341807,123.156745 elev455 ft
2. Cloudy daytime dry pavement
3. Photos attached
4. Travelling east on level road at less than 10 mph. Slowing down. Went through stop. Hit by truck travelling south down a moderately steep incline.

 

Excellent:

There is a paving artifact I've not seen before:
49.341807 N 123.156745 W - Google Maps

The diagonal that passes left to right under the driver wheel. On the right is an ordinary patch seen before in many other photos. It is the diagonal on the left that is different. From another direction:
49.341807 N 123.156745 W - Google Maps

I get the impression of a lateral slope too but I curious about your earlier posting:

• Sold Prius - you don't have a way to replicate the problem?
• Reported to NHTSA - they take Canadian reports?
• Was it the 1.5L, NHW20 model, smooth rear lenses or 1.8L, ZVW30 with the angular indent rear lenses?

Thanks,
Bob Wilson

 

Firstly, let me thank you for taking the time and for taking this seriously. We use this intersection 3 or 4 times a day. The pavement is smooth. The patches are not noticeable. It is also level.

We sold the Prius back to the dealer in trade as we were not comfortable driving it or selling it privately. We traded it a few hours after getting it back from the body shop.

We reported to NHTSA on line. There was no trouble filling in the form and they published the complaint. We also reported to Transport Canada and Consumer Reports. In both cases they phoned us to confirm the information

It was a 1.5 litre with 16000 km.

 

Thanks! The Google Street View has strengths and weaknesses. I could see the 'joints' but no way to measure their effect.

Again, thanks! I'm interested in facts and data to try and replicate or understand what is going on. I take it the one accident was the only time you had a brake problem?

I don't fault your decision to move to another vehicle. It just makes it harder to replicate the problem. I do appreciate clarification of the model.

I suspect there is an as yet undiagnosed or fully documented brake problem with the NHW20. But I would have to rent one to replicate it myself. This is just a little more commitment than my curiosity.

I'm still looking for a volunteer who can replicate the problem. I'll loan them an accelerometer and work on the analysis.

Bob Wilson

 

I have driven my Prius for 8 months now and it has exhibited the problem in several situations. I am ready for it and I compensate by pushing harder or by quickly releasing and reapplying the pressure.

I think that the problem in the Prius stems from the fact that the brake pedal pressure is somewhat simulated due to the "break-by-wire" system. When hitting a bump in the road where the breaks release due to an anti-lock event (yes all cars release pressure sensing wheel skid) the Prius does not push back on the break pedal (other cars usually give the driver a source of feedback through pedal push-back). The drivers reaction when feeling nothing is to sense the car is surging. It is NOT surging. I have driven throttle by wire cars that exhibit an opposing function. When driving (on cruise control or at steady speeds) and I hit a relatively large bump, the car feels as if the breaks are applied (my wife and daughter both stated this). The breaks are NOT applied but the sudden loss of throttle (due to anti-skid computer function) with no inputs from the driver cause the feeling that the opposite function is occurring. If your foot is on the throttle and the car slows due to electronic removal of the throttle the driver "feels" a breaking action (especially in manual transmission at lower gears). If your foot is on the break and the car electronically releases the break due to an anti-lock event (sensing wheel slippage) the driver may sense that as acceleration.

 

I can't believe people saying this problem is not a problem even after Toyota has admitted it is and issued a recall. Please, stop with that line of reasoning. Because it is not reasonable. For the record I've had no issues in mine one way or the other.

Now, it is possible that any post-recall reports are more than anything else erroneous and could be answered by posts along the lines of the one above with the feedback and the brake by wire.

 

Ah, but it *is* reasonable. The post above is spot on in explaining why people perceive this as a problem.

It is a problem in the sense that some people perceive it as one, but it's not a problem in the physical sense that something isn't working or that the brakes are dangerous.

As for pre fix verses post fix, please recall that this thread relates to the 2010 brakes after the fix.

Tom

 

I am of the same mind as sgm0815 (Martin) posted on page 8. But, as I have the same *exact* problem as described in the OP, I still want to add my data point to this discussion. I have a Gen3 with 4K miles. A pothole recently formed on an exit ramp that I travel regularly that ends in a stoplight. The first few times I encountered the pothole, I wasn't prepared to dodge and I experienced the "surge"--a momentary (1/2 second) feeling of a loss in braking power at a constant pedal pressure. The feeling is very unnerving. It's not an ABS shudder. I've owned ABS cars for 20 years. I have never owned a hybrid before this.

The surge is so sudden and so brief, I have no time to react and normal stopping force resumes so quickly, I'm not sure my stopping distance is actually compromised by much more than a few inches. Heck, it might not change stopping distance at all—just the weird change in pedal pressure makes it seem like distance is increased.

As another data point, I am an amateur race car driver, racing roughly 20 times per year for the last ten years. I probably have a fairly good feel for braking at the threshold of tire adhesion and an above-average ability to react to pedal pressures and modulate same. Probably without even noticing it at this point. I don't know how that affects my experience and perception. I notice that both steering input and brake feel are not “normal†to me. With steering, I feel like the car “wanders†at speed and my normal subconscious steering corrections are not usable. I almost feel like the wind is blowing me around more than other cars (maybe it is). Other than 10 years of occasional Honda Odyssey driving, I’ve only owned BMWs and Porsches as daily drivers. That probably sounds awfully snobbish, but I only mention that as (yet) another data point .

Supposedly, the brake fix was applied before I picked up the car. In toyotaownersonline, I show two warranty services as being performed:

CAMPAIGNS ~|~A0B ~|~A0B ~|~A0B
PDI ~|~PDI ~|~ ~|~46TOZ 001013

Is A0B the brake fix?

BTW, I see this as an academic exercise. I have no plans to sell my Prius and buy a Hummer .

Steve

 

The ABS dropout discussed in this thread is not the same as ABS shudder. The dropout occurs when the ABS system reduces the overall braking force in an attempt to get the wheel to roll. The shudder comes on when the ABS system pumps the brakes automatically. As others have posted, this dropout occurs when other non-hybrid vehicles - not all vehicles, but many others.

As an aside, many modern ABS systems, like that found in the Prius, no longer have a detectable shudder when automatic brake pumping occurs. The modulation frequency it too high to feel as a shudder.

Tom

 

The problem with potholes is paving crews respond pretty quickly. Here two I've used in my experiments:

This one was patched before the brake fix came out.

This second pot hole showed up a day before I got the patch. I was able to baseline the pre-SSC-A0B fix and retest later showing the brake pause was gone:

The deepest part is higher than my ankle and the length over 6 ft. But the pothole is history as it was fixed the next week.

Do you have a local speed bump that you can use to replicate the anomaly?

We know 19 mph is a threshold speed to the brake system. You might try at speeds under and over 19 mph to see if you can replicate the problem. In Huntsville, I had to also wait for a light drizzle.

There has been at least one report of the SSC-A0B not being properly applied. The owner returned and they used their diagnostic scanner to read the software version. This would be a reasonable request on your next visit to the dealer.

If you replicate the speed pause, send me a PM and I'll loan an accelerometer to measure the effect:

With the accelerometer, we can quantify the effect.



Bob Wilson

 

Are those cat hairs - or scratches in the black plastic. If scratches, maybe we need a new thread on tray durability

I'm on my 2nd 2010 - first one had the 'problem' - this one (new MFG date March) had the 'problem' yesterday. I'm not reading all the posts - just throwing in an observation...

The 'loss' of braking was almost nothing. It was a non issue (it was an issue on my previous car). The loss was so short, it meant nothing.........

 

Terrier-Pekinese mix, Kiwi dog.

I need a description of how to recreate it. I can't do it since the fix.

Bob Wilson

 

I've only felt noticeable momentary perceived loss of braking power a couple of times, both before the Toyota update.

The pedal resistance appeared to vanish during the event and with no resistance I did not not achieve constant pedal pressure. I interpreted this as a perceived of loss in braking power at constant pedal position.

You mentioned a feeling of loss in breaking power at constant pedal pressure. You also mentioned it being over before you could react

Did you mean constant pedal position or were you able to maintain constant pedal pressure without reacting at a conscious level?

 

It felt as if I lost then regained pedal feedback pressure. I'm sure I tried to maintain constant foot pressure, but I also felt as if I backed off a bit when I felt the change in feedback. I've overheated brake fluid in the past and lost hydraulic pressure. My natural reaction to that would be back off and pump the pedal. So, I might have been reacting subconsciously in that way. But, it was so sudden and accompanied by an unexpected pothole bump, so I'm only relaying perception. I've no idea what the reality was.

Steve

 

Just curious. Is your rudeness congenital or acquired?

 

I had my recall service done a few months ago and notice it happening less often than before the service. It doesn't go away completely like I hope it would. Never noticed this problem in the 9 years I had my BMW.