Gen III Prius ~ TURN OFF!

Did anyone consider that since the floor mat may have caused the throttle to stick wide open, at the same time it may have prevented the brakes from being fully applied?

 

This family was going down a 10-12% grade with one 25 mph an exit or an intersection to look forward. He had already over heated the breaks, attempted to get the car in neutral with no success. This California Highway Patrol Officer was in a now win situation.

 

I agree, sadly doing 120 MPH with a carload of your loved ones is not a time to think logically, so I do not think we can rule it out.

Here on Priuschat we often have threads about B mode and when to use it. Long down hills where extended braking may over fill the HV Battery and begin using friction braking, overheating them is the example I always use.

http://priuschat.com/forums/gen-ii-...what-b-gear-shift-joy-stick-2.html#post956741

If he HAD been driving a Prius, one would hope he had used B mode, so his brakes were not already over heated when the gas pedal got stuck. Even in D, until the HV battery was fully charged, it would have used regenerative braking, not heating the disc brakes.

If a LONG downhill slope threatened to overtax the brakes just before a failure pegged the accelerator, the Prius is the car I would WANT to be in.

1) It is possible, as a driver, to choose between 3 different methods of braking: Regenerative Braking, Engine Braking, and Friction Braking.

2) In many cars, if you shift to neutral with the accelerator floored you will destroy the engine, the Prius ignores the accelerator in neutral.

3) The Prius has the governor set to a very low top speed comparatively, 108 MPH.

4) Many 'wrong' choices put you in neutral, Park or Reverse at over 5 MPH, as examples.

However, as a loaner, it is entirely possible for the driver not to know any of this. A lot of experience with a patrol car (Ford Crown Victoria, Chevy Caprice, etc.) does not imply expertise in a Lexus. (or, hypothetically, in a Prius)

 

How do we know this?

 

Lets put some facts and data in the thread:

ACCIDENT LOCATION

• 32 50' 18.90" N 117 00' 11.39" W
• intersection: 9001 Mission Gorge Road, Santee CA
• vehicle direction: north on State Highway 125
• State Highway 125 ends at Mission Gorge Road
• highest elevation 245m, 2.1 miles from intersection at 99m
• date: August 28, 2009, 6:36 pm, cell phone call from vehicle
• view intersection: Google Earth or Google Map
• approach to intersection

VEHICLE CHARACTERISTICS

	Column 1	Column 2	Column 3	Column 4	Column 5
0	Lexus 350 es	Prius ZVH30	characteristic
1	272 hp	134 hp (peak)	engine power
2	137 mph	108 mph	top speed	limited
3	6-speed ECT-i	CVT hybrid	transmission
4	disc	disc	brakes
5	3	580 lbs	3	042 lbs	curb weight

​

SYNOPSIS

• Lexus 350 es != Prius 2010 (ZVW30)
• Engines are different
• Transmissions are different
• Vehicle weights are different
• Top speeds are different

There is nothing about the Lexus 350 es that applies to the Prius but the Prius has unique features that would mitigate a killer floor mat induced accident:

1. Shift into "N" - move shifter to left and hold for ~2 seconds, all power to the wheels stop but electric steering and power brakes continue to work
2. mechanical parking brake to rear disc brakes - a significant part of the braking system would work to stop the car ... assuming the killer floor mat didn't also jam under the parking brake
3. lift feet and reach down to grab killer floor mat and pull it out of the floor area - then apply brakes and come to a stop on the shoulder

Other follow-up as appropriate: letter to the National Highway Traffic Safety Board and copy to local Toyota dealership.

MACGYVER MOMENT

script: You are in a run-away vehicle with steering but the throttle is jammed open and the brakes are not working and the shifter is not working ... what do you do?

1. tell everyone,"TIGHTEN YOUR SEAT BELT WE ARE GOING TO CRASH!" - ignore any chatting, you are trying to have a survivable crash
2. push parking brake in - of course the brakes don't work but the mechanism being jammed in will let the accident investigators know every attempt was made to stop.
3. use body of car as brake against guard rails (if available) - steer to treat the side of the car as a brake shoe and try to slow down the car. There is a risk of rolling the car.
4. steer to a 'high center' ditch - get one drive wheel in the air so no more power will try to power the car and the bottom of the car will be the brake shoe. There is a risk of rolling the car.
5. steer into a field with brush, no trees - this uses the body as a brake shoe as well as lifting the wheels so they are less able to transfer power. There is a risk of rolling the car.
6. ask passenger to open cabin fuse panel and pull all fuses - if an engine control fuse is pulled, it will stop and reduce speed. This assumes one knows where the cabin fuses are located and they can be reached while the car is in operation. It will give the passenger something to do.
7. try to induce a power slide - steer briefly to right and then a hard left, maximum turns, and try to get the car to spin about the vertical axis. You want the tires sliding sideways to be the missing brake shoes. There is a risk of rolling the car.
8. try to blow-out and destroy one tire - steer for a curb and try to destroy one drive wheel to stop power transfer to the wheels and get parts of the body to rub against the earth to begin working like a brake shoe. There is a risk of rolling the car.
9. try to clip a delivery van or truck - you want an impact severe enough to trigger the air-bags since this also cuts the engine, tightens the seat belts and puts the car in automatic 'crash mode'. Do it as early as possible. There is a risk of rolling the car and a hazard to the delivery van or truck.
10. try to take out a road sign, one of those light weight, single support informational signs so it will trigger the air bags, which will cause the engine to shutdown.
11. sacrifice the vehicle and any and all road-side property to stop the car ... stuff can be replaced ... people are much harder to replace.

INAPPROPRIATE FOLLOW-UP

• blame Prius control software and computers because a non-Prius accident occurred
• second guess the driver without first looking at what they saw
• start a thread with a totally misleading, inaccurate, title about an accident that did not involve a Prius

Bob Wilson

 

well i heard about the accident which appears to be primarily mechanical due to the floor mat not properly anchored. but all this talk about what is strongest, the brakes or the accelerator is confusing...

it takes 1300 feet to accelerate to 70 mph or it takes 120 feet to brake from 60 mph, well i would have to assume that in either instance only on action was at work, either braking or accelerating. i dont know of any stats on stopping power while both are working at one time.

but the other thing is, if its drive by wire? why is the accelerator still working if the brakes are depressed? does it make sense to allow both to work at the same time?

 

It is a Lexus 350 es with a computer controlled, geared, mechanical transmission, nothing like our hybrid CVT transmissions. Nothing in our Prius experience applies:

• different engines with an addition 138 hp
• different control systems due to transmission
• different vehicle weights, nearly 500 pounds heavier
• different size disc brakes

Bob Wilson

 

Does the Lexus have an electric motor drive?

 

They are in opposite directions, you will subtract the weak force causing you to speed up from the strong force causing you to slow down, you will be left with a weaker force causing you to slow down. My real life experience with this is a Ford Windstar minivan, but you don't see me trying to scare folks about all minivans.

No, the lexus is not a hybrid, this is just an excuse to create FUD about hybrids to scare people.

 

No. The Lexus 350 es has a six-speed, gear transmission that is computer controlled. It has nothing in common with the Prius or any of the Toyota hybrids.

Bob Wilson

 

I think this part is aimed at me. I am not blaming anything on the computer system. All I was suggesting was the possibility of a computer error that corrupted data causing chaos in the engine/drive system.
For instance, and I will take the Prius as an example because I do not know the Lexus systems (nor the Prius for that matter), if corruption caused MG1 or MG2 to apply full power to the front wheel drive mechanism, then the brakes would have extreme difficulty in stopping wheel rotation because of the torque of the electric motor(s). At the same time, that corruption may prevent the drive selection from working, causing the drive to remain where it was selected. Who knows, may be it could inhibit turning off the power.
I seem toremember a Prius decided it had a mind of its own and took off. Was the cause of that accident ever determined?

Edit

Sorry for foot in mouth, Bob, I thought the Lexus drive system was similar to the Prius.

 

VEHICLE: Lexus 350 es

It looked something like this when new:


Now it looks like:


THOSE INVOLVED

• Mark Saylor, 45, <photo available>
• Cleofe Saylor, 45,
• Mahala Saylor, 13, <photo available>
• Chris Lastrella

This was the accident and deaths used as introduction to this 'question':

I have absolutely no questions for you ... none.

Apology accepted.

I've already shared my thoughts with others.

Bob Wilson

 

Aquanaut,

Your second post allows us all to see more clearly what your original
intent was. I can now see that it was your presentation and not
your intent that raised my suspicions.

An earlier second post would have clarified the situation much
earlier, an unfortunate consequence of your being "a busy guy."

As it was not said at the time of your first post:

:welcome: to PRIUSchat.

 

Aquanut,

I really appreciated your first post, and I think it should "raise" awareness not only to the public when renting vehicles, but as a whole. The technology on all vehicles has changed a lot, and after reading a lot of the posts here, you can see some people who have had their old cars for 10 years more or less. No not everyone, but a good sampling are not car traders every 2 years.

I myself, from your post took a second look at "what to do?" given a scenario like was encountered. No one has time to read an owners manual (if even included) on a rental/loaner vehicle. Those safety issues must be told at the time of rental and be given to the "renter" or Loanee at such time. Of course, the floor mat thread has been discussed in detail, and we all know that is WRITTEN in the Toyota manuals as well. I believe they are as well in the Lexus. But in any event your original post was to raise concern and I still appreciate that intent.

I spoke to my service department on a recent visit to pick up "accessories" to ask the specific question of how to turn off the vehicle in an "Emergency". Was told to "Hold down the power button for approximately 3 seconds and the system will shutdown". I would never have known that without this post. And I do Thank You for that.

Sorry for my initial Ranting, but people have to ask questions too, we are to much in a "RUSH" society and don't take the time sometime, to ask the IMPORTANT questions on a rental, vacation auto rental etc. We as society need not assume something works as X but really it's Y. If it is determined that the Officer only had to hold a button in for a number of seconds to shutdown the vehicle, it was really sad that all those who perished in the Lexus crash were not told this at time of drive off.

Again thanks for "AWARENESS" Training to all of us, no matter what vehicle is driven. It's not a Toyota or Lexus issue but an Automaker question for all of us to know.

 

You *are* new here if you expected a thread to stay focused and on-topic. That's the interesting thing about posting: starting a thread does not give the OP ownership. Once you post, the thread has a life of its own.

Tom

 

One way to promote a hypothesis is to do the experiment:

• shift to "N" at any speed - this is easy to replicate although best first done without any traffic around. I've done this often in my pulse and glide testing and it is perfectly safe although it should not be done on a downgrade due to the rapid increase in speed. However, the power steering and brakes continue to operate normally ... there is no risk of a sudden change in handling.
• press and hold "power" - again, easy to replicate but definitely needs to be done without any traffic around. I've not done this because it looks to be a 'one way' test ... the car will have to be brought to a stop and operation of the parking pawl is undefined. I tend to avoid experiments that may risk my vehicle. Others have pointed out the vehicle handling will change with the "power" off.

In aviation, we not only teach safety but practice emergency procedures too. This includes having an instructor pull the power and the pilot in command doing everything that leads to a power-off landing (I've 'harvested' hay with my landing gear.) Landing at a grass strip by treating it as a 'power-off' landing is one of the best ways to hone ones skills. The key is practice, not just discussing a theory, but actually doing the experiment. That is why no one died in the recent Hudson River landing of an AirBus.

The wise pilot also subscribes to and reads the accident summary reports. We don't do it out of a gholish voyeurism but because it reminds us that flying is potentially dangerous. It reminds us to be ready and think about what we learned in our training ... and application of the lessons learned. Sh*t happens and survival is dependent upon rapidly switching from 'normal' to the new flight conditions.

I know what happens when either of our Prius finally runs out of gas because I've done the experiment. One, the NHW11, throws up a lot of warning lights but is no big deal as the traction battery provides enough power to drive to a safe place. The ZVW30 is a little too stealthy for my taste, no final warning lights. It also switches to traction battery power that can quickly drain and leave the vehicle without any motive power to reach a safe place to park. But I know how to handle each because I've done the "forbidden" experiment.

Now if I decide to try the "Power" switch experiment, it will be in a rental with full insurance coverage. I have no problem risking someone else's insured vehicle ... first. Later, I'll have no problem replicating it with ours. What I don't know (and I've not yet read here) is how the parking pawl works when the vehicle is powered down and rolling. This is called a "forbidden" experiment because parking pawl operation in this case is undefined.

I just recently got Volume II of the 2010 Prius repair manual. I'll see if there is an easy way to disable the parking pawl with it in the "open" position. If so, I have no problem with replicating the "Power" emergency procedure. The key is whether or not parking pawl engagement requires a power or if it is 'spring' or default operated to the closed position.

Bob Wilson

 

problem is, once you go down the "what if ..." road, it means nothing more than if you said, "what if the prius had old fashion cable linkage ... and it got stuck ... and it ..."

The whole topic is similar to the old "lost traction on ice, then lost power" topic. The ice pro's jump in saying, "bahhh, you just don't know what you're doing ... because WE never have problems on ice ... you just don't know how to drive". The traction/power loss group then jump in, and it gets even more inflamitory. Same thing - different issue.

.

 

I also was concerned about the apparent inability to turn off the car in the event that the throttle (or cruise control or some other electronic miscreant) caused a run-away problem so today I took my 2006 Prius up to top speed (open road, no one around) and held down the gas pedal and the Start/Stop button and, sure enough, the engine stopped. New issue -- although I then was going about 95 mph (and it was very easy to steer, so don't worry about losing power steering), it wouldn't re-start! I tried applying the brake and, of course, shifting to neutral, but it wouldn't start till I came to a complete stop. I then turned off the power, put it in park and then pushed the power button. It started immediately and ran fine, although the red triangle and the yellow check engine both stayed illuminated for the final twenty minutes of my drive, when I then stopped and parked the car at my meeting. When I came out about two hours later, all was fine (and the lights didn't come on).

 

It was an accident that involved an off duty police officer and his family. Some how to floor mat got stuck on the accelerator and caused a deadly wreck. The car wouldn't turn off so they crashed at the end of the road.