On Wed, 3 Mar 2010 11:32:12 -0700, "chaniarts"
wrote:

AZ Nomad wrote:
On Wed, 3 Mar 2010 11:03:39 -0700, chaniarts
wrote:
wrote:
On Mar 2, 9:01 pm, (Doug Miller) wrote:
In article ,
(Don Klipstein) wrote:
In , Doug Miller wrote:
The thing that really stood out to me was the statement by
Toyota's president that they're going to look into programming a
brake override for the throttle.

I have only one question: WHY IN GOD'S NAME WAS THAT NOT THERE
FROM THE BEGINNING?

*Programming* a throttle override by the brake? As in relying on
lack of electronic malfunction in order to have the brake reliably
apply an override onto the throttle?

Since the override becomes necessary only in the event of a
throttle malfunction, for the override to not work would require a
second malfunction.
Clearly two simultaneous malfunctions are *far* less likely than
any single
malfunction.


That's obviously totally false. Let's say I have a single computer
that is running the throttle, the shift interlock, and the engine
shut off via the start/stop button. Actually that doesn't sound
that far fetched. Clearly you could write a program in such a way
that the program under certain conditions goes into a program loop
where it will no longer respond to either a change in throttle
input or the stop button and will also not unlock the shift.
That's a single program failure, not two simultaneous malfunctions.

but most modern cars have probably 30, and some upwards of 100,
different computers.

Wether or not there's a door lock computer is irrelevent.

There's just one controlling the engine, the ECU.

Do you have some insane notion that there's one computer for each
spark plug and another bunch for the injectors, etc?

no.

however, there are multiple computers controlling the engine, and all it's
assocated subsystems, at least on mine, which is a 94. one would assume that
more modern cars have more computers to better control emissions, since the
current laws are much more strict than in 94.

Your assumptions are wrong 1994 was pre OBD2 - with the mandated OBD2
system the entire power train is controlled by one computer.

all the functions don't have to reside within one computer. they are
networked together and cooperate and share data amongst themselves.

But that does not meet the OBD2 requirements.