Toyota Runaway Cause: Electronic Throttle/Cruise Control?

C. E. White wrote:as/
>
> I would bet that this is mostly crap. The guy driving the Lexus that got
> all the attention was an idiot. How could he not put the car in neutral?
> Even my 82 year old Mother knows to do that. I tried it on her Higlander
> today ... works no problem (well except the engine wasn't racing out of
> control since her floor mats are properly secured).
>

Consider the Prius is drive by wire and shift by wire. Also, the car
has ABS. Theoretically a signal could hold the brake bypass open. A
computer malfunction could cause a lot of havoc.

I have owned two cars that had a sticking throttle problem, but they
were both stick shift and my first impulse was always to depress the
clutch. Since my new Prius is automatic (and computer controlled at
that) I am a bit worried. I am thinking of engaging parking brake and
testing full throttle. The parking brake does seem to be a purely
mechanical deal.

Before my retirement I worked in the aerospace industry, and have seen
products (not from my employer but from another company) that made me
feel uncomfortable in their fly-by-wire implementations. And those were
quad redundant. I suspect my Prius control computer has NO redundancy.

hls wrote:
>
> "C. E. White" > wrote in message news:hcum2j$bn1
>>
>> However, I still say if the guy had moved the shifter into neutral, he
>> could have stopped the car. But that is jsut my opinion.
>>
>> Ed
>
> I tried this technique and there is nothing to stop you from flipping
> the shifter up to
> neutral. You might over-rev an engine (especially if the electronics
> have rebelled)
> but you will be able to slow and stop. The brakes dont stop working if the
> vacuum is lost...you just have to depend upon your leg muscles. You may
> THINK
> you have lost all brakes, but they are still there.


Ah, but some of the Toyotas are shift by wire. That is, there is no
physical linkage, merely a switch that sends a signal to the computer.

And, keyless ignition. The ON-OFF switch sends the shutdown signal to
the computer. I have a Prius, and I'm a bit worried.

C. E. White wrote:
> "E. Meyer" > wrote in message

>> "The guy was supposedly..."; "Supposedly the car was a Lexus...";
>> "Since it
>> was reportedly a rental..."
>>
>> I feel like I'm reading a court transcript or a CYA newscast. Are
>> you guys
>> all lawyers?
>
> No. I just resist stating information as facts known to me when I am
> repeating things reported by the press. If you review a bunch of web
> sites you can get a pretty good picture of what happened in this one
> particualr case.
>
> http://www.10news.com/news/20831532/detail.html
>
> That report refers to the car as a loaner, not a rental. It mentions
> all weather floor mats as a potential cause. It also implies the 911
> call lasted at a relatively long time.
>
> http://xmb.stuffucanuse.com/xmb/viewthread.php?tid=6395
>
> This one mentions that the car had all weather loor mats that were
> longer than the correct ones for the car.
>
> http://www.ennislaw.com/toyota_floor..._10262009.html
>
> This one mentions that the mats in the car were actually mats intended
> for a Lexus SUV and that they were not properly secured. My Mom's
> Toyota Highlander has two clips that very securely locate the floor
> mats. As long as the mats are proplerly installed I can't see haw they
> could cause a problem.
>
> This site also mentions that the car would lose braking power with the
> throttle wide open. This is true for any vehicle that uses engine
> vacuum to provide brake boost, not just a Lexus or Toyota. The booster
> only stores enough enough vaccum for a few stops. An engine at WOT
> doesn't provide any additional vacuum. So if your throttle is stuck
> wide open, and you repeatedly press on the brakes, you will loose
> boost.

Supposedly these cars use hydraulic pressure supplied by the power
steering pump for braking assist not engine vacuum. Well, that's what I
hear anyway.

>
> However, I still say if the guy had moved the shifter into neutral, he
> could have stopped the car. But that is jsut my opinion.

Odd, ain't it?

>
> Ed
>
>

In article >, dsi1 > wrote:
>C. E. White wrote:
>
>Supposedly these cars use hydraulic pressure supplied by the power
>steering pump for braking assist not engine vacuum. Well, that's what I
>hear anyway.

It makes good sense, if the engine isn't going to be running most of the
time anyway.

The old BMW E28 did something similar. It worked very well, and it included
a pressure reservoir that provided considerable braking for a good while after
the engine was shut off. It was substantially more complicated than it needed
to be and had dozens of seals that all went bad at the same time, mind you.
But that has more to do with the implementation than the concept.

>> However, I still say if the guy had moved the shifter into neutral, he
>> could have stopped the car. But that is jsut my opinion.
>
>Odd, ain't it?

Dunno, I have never driven one of the hybrids. I'm still commuting to work
in a car with a manual choke. It's paid for.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Scott Dorsey wrote:
> In article >, dsi1 > wrote:
>> C. E. White wrote:
>>
>> Supposedly these cars use hydraulic pressure supplied by the power
>> steering pump for braking assist not engine vacuum. Well, that's what I
>> hear anyway.
>
> It makes good sense, if the engine isn't going to be running most of the
> time anyway.
>
> The old BMW E28 did something similar. It worked very well, and it included
> a pressure reservoir that provided considerable braking for a good while after
> the engine was shut off. It was substantially more complicated than it needed
> to be and had dozens of seals that all went bad at the same time, mind you.
> But that has more to do with the implementation than the concept.

The advantage of a vac boost system is simplicity. OTOH, there's cars
where fitting that big booster thingie just ain't practical. OTOH, even
though your old BMW had it, the system still seems high-tech and exotic
these days and my guess is that it's a selling point on high-end cars.

>
>>> However, I still say if the guy had moved the shifter into neutral, he
>>> could have stopped the car. But that is jsut my opinion.
>> Odd, ain't it?
>
> Dunno, I have never driven one of the hybrids. I'm still commuting to work
> in a car with a manual choke. It's paid for.

I sure hope that it's paid off. Those things disappeared with carburettors!

The cars I had with chokes were set by pressing the accelerator to the
floor once. I had one Brit car with a real dash operated choke - just
don't forget to push that sucker back in! :-)

> --scott

"C. E. White" > wrote in message
...
>
> "ransley" > wrote in message
> ...
>
>> > The guy was supposedly a highway patrol officer....I just find it hard
>> > to believe they had time to make a 911 call and not time to put the
>> > car in neutral. I can understand the confusion with the start/stop
>> > button if it was a rental, but not the shift level.
>> >
>> > Ed
>
>>Or turn off the key and put on the parking brake
>
> Supposedly the car was a Lexus with the Start/Stop button. With the car in
> gear just pushing this button does nothing - you have to press and hold it
> for three seconds for it to kill the engine if the car is in gear. Since
> it was reportedly a rental, I can understand the driver not knowing this
> fact. However, I still cannot imagine him not putting the car into
> neutral.
>
> And why call 911? Did they figure Scotty was going to beam them out of the
> car?
>
> Ed
Under the circumstances, panic was very likely a factor. Putting one's car
in neutral under such unusual circumstances is not a conditioned response.
The 911 call from the back seat was a futile attempt to clear traffic.

"dsi1" > wrote in message
...

> Supposedly these cars use hydraulic pressure supplied by the power
> steering pump for braking assist not engine vacuum. Well, that's
> what I hear anyway.

For sure some cars use hydraulic brake assit instead of vacuum assit
for the brakes (my 2001 Mustang GT did for instance). However, the
reports I read indicated that the Lexus in the California wreck used a
vaccum booster (and the Lexus parts catalog supports this).

Hydralic type boosters depend on the engine running to provide
hydraulic pressure. You can include an accumulator in the circuit to
provide back up boost for sutuations where the engine dies, but this
is still limited.

I am not sure what the hybrid vehicles use. A hybrid you can't depend
on either engine vacuum or an engine driven hydualic pump to provide
brake boost, so I assume they have an electrically driven hydraulic
pump to provide the boost but I don't know for sure. Maybe they use
the ABS pump....

>> However, I still say if the guy had moved the shifter into neutral,
>> he could have stopped the car. But that is jsut my opinion.
>
> Odd, ain't it?

Yes. I guess even trained professionals can panic.

Ed

C. E. White wrote:
> "dsi1" > wrote in message
> ...
>
>> Supposedly these cars use hydraulic pressure supplied by the power
>> steering pump for braking assist not engine vacuum. Well, that's
>> what I hear anyway.
>
> For sure some cars use hydraulic brake assit instead of vacuum assit
> for the brakes (my 2001 Mustang GT did for instance). However, the
> reports I read indicated that the Lexus in the California wreck used a
> vaccum booster (and the Lexus parts catalog supports this).

Thanks for that info.

>
> Hydralic type boosters depend on the engine running to provide
> hydraulic pressure. You can include an accumulator in the circuit to
> provide back up boost for sutuations where the engine dies, but this
> is still limited.
>
> I am not sure what the hybrid vehicles use. A hybrid you can't depend
> on either engine vacuum or an engine driven hydualic pump to provide
> brake boost, so I assume they have an electrically driven hydraulic
> pump to provide the boost but I don't know for sure. Maybe they use
> the ABS pump....

That's a good question. I would suppose you could even use the drive
motors to slow the car down. Hybrid cars are such a complicated animal.

>
>>> However, I still say if the guy had moved the shifter into neutral,
>>> he could have stopped the car. But that is jsut my opinion.
>> Odd, ain't it?
>
> Yes. I guess even trained professionals can panic.

My guess is that you don't really know how you'd act in such a situation
until it happens. Good thing this is such a rare event.


>
> Ed
>
>

"C. E. White" > wrote in message
...
>
> "dsi1" > wrote in message
> ...
>
>> Supposedly these cars use hydraulic pressure supplied by the power
>> steering pump for braking assist not engine vacuum. Well, that's what I
>> hear anyway.
>
> For sure some cars use hydraulic brake assit instead of vacuum assit for
> the brakes (my 2001 Mustang GT did for instance). However, the reports I
> read indicated that the Lexus in the California wreck used a vaccum
> booster (and the Lexus parts catalog supports this).
>
> Hydralic type boosters depend on the engine running to provide hydraulic
> pressure. You can include an accumulator in the circuit to provide back up
> boost for sutuations where the engine dies, but this is still limited.
>
> I am not sure what the hybrid vehicles use. A hybrid you can't depend on
> either engine vacuum or an engine driven hydualic pump to provide brake
> boost, so I assume they have an electrically driven hydraulic pump to
> provide the boost but I don't know for sure. Maybe they use the ABS
> pump....
>
>>> However, I still say if the guy had moved the shifter into neutral, he
>>> could have stopped the car. But that is jsut my opinion.
>>
>> Odd, ain't it?
>
> Yes. I guess even trained professionals can panic.
>
> Ed

Good question on hybrid brake assist. The power steering system uses an
electric motor to provide assist, and so there is no electrically driven
hydraulic pump for the power steering system. I would imagine that hybrids
use some kind of electric assist for the brakes. The ABS system on a Toyota
does not have a pump, just valves that open and close rapidly to modulate
brake force to individual wheels.
--

Ray O
(correct punctuation to reply)

On Thu, 05 Nov 2009 08:11:51 -0600, hls wrote:
> The brakes dont stop working if the
> vacuum is lost...you just have to depend upon your leg muscles. You may
> THINK you have lost all brakes, but they are still there.

Yes - only had it happen to me once (coil lost power and so the engine
died) but I was running at around 80 at the time and it was something of a
surreal experience. I think the split second before I realised what was
going on was perhaps stranger, as the car began to slow due to the rear
wheels turning the dead engine.

Our truck's old enough to have no engine assist for the brakes at all, so
the leg gets a good work-out :-)

cheers

Jules