Toyota UA-LAC

[john at westcoastgarage.net]

Huw Powell wrote:
> I agree that a software flaw/glitch/bug could be a big factor here.
>
> These cars aren't like my 80s Audis or my 70s truck, pretty much every 
> "feature" is mediated by a/the computer, right?
>
> - the throttle is controlled by a computer, not a cable
> - the brakes are run by a computer, not your foot pressing on a column 
> of fluid
> - the transmission isn't just a bunch of gears one can disengage with 
> a  lever
>
> etc. etc.
>
> Some random thoughts - trying to brake at WOT and high speed with a 
> full-on ABS/traction control system might result in inability to brake 
> as hard as possible (each time the ABS pulls pressure off the pads, 
> aren't they now "dragging" for a moment?).
>
> It might not be possible to put tranny into neutral at speed.
>
> It might not be possible, even, to turn off the engine with the car 
> moving for safety reasons (you'd be turning off everything else with it).
>
> And lastly, just for fun, braking against 200hp at the wheels (a 
> reasonable figure these days) generates about 37,000 watts (50 * 750) 
> of energy at each brake (more at front, less at rear).  That's a *lot* 
> of heat.  Although my assumption that all the engine hp have to be 
> converted as fast as they are made might be wrong ;)
>
> Ed Kellock wrote:
>> In addition to the 3-second press to turn off the ignition being 
>> maybe too
>> much for some drivers to manage in such a crisis situation, if indeed 
>> there
>> is a software issue, then the 3-second turnoff operation might also be
>> ineffective.
>>
>> Ed
>>
>>
>> Unfortunately, some of the car in question also have the "smart key" 
>> system
>> in them, in which a button is used for shutdown. Unfortunately, it 
>> has to be
>> held in for 3 seconds to work, which is an eternity when in this 
>> situation.
>>
>> I'll agree with John on this one, I think it's a software problem. I've
>> though this since learning about the problem and looking at my wife's 
>> car.
>> There is no such issue with my wife's 05 camry 4-cyl, which is 
>> throttled by
>> a cable. But, these cars in question are throttle by wire, and I 
>> think just
>> the right circumstances bring out a bug that holds the throttle wide 
>> open.
>>
>> Just my .02,
>> Tony
>
>
>> .  As for the sticking throttle, I firmly believe,
>>>> and never surface in the media, that they have a massive (and VERY
>>>> scary) software problem, compounded by Toyota's "taking a chance" 
>>>> by choosing to forgo the "failsafe" used by European manufacturers.  
>
I don't think electronic braking is on the market yet.  It's just 
appearing in the trade mags, though.  The trannies have an electronic 
control component, but (at least in the German cars) they're still 
mechanical.  As for the ABS, since the CU reads the difference in wheel 
speed, I would think it wouldn't enter into a scenario of the 
simultaneous full lockup of all 4 wheels.  I freely admit a lack of 
experience in ABS, as we don't have anything like weather here 
...............  John