
An Engineer’s Eureka Moment With a G.M. Flaw - wallflower
http://www.nytimes.com/2014/03/29/business/a-florida-engineer-unlocked-the-mystery-of-gms-ignition-flaw.html?hp
======
tsomctl
_that an unsuspecting driver could bump the ignition key and cause the car to
cut off engine power and deactivate its air bags._

I didn't know that turning off the ignition would deactivate the air bags.
I've welded on vehicles before, and have talked to body work guys about it.
Everyone says to disconnect the battery so you don't accidentally set off the
air bags. It can happen by stabbing the mig wire into the air bag harness, or
just by letting the welding lead lay next to it and inductively causing
current to flow.

Seems like if you're parked in a parking spot, and someone smashes into you
hard enough that the acceleration can trigger the airbags, you would want the
airbags to go off. I don't know why you would ever want to disable the airbags
(except baby in car seat).

~~~
Zigurd
The airbag sensors require power, and would, perhaps only eventually, drain
the battery. I use a bluetooth adapter on my OBDII port and I suspect this
very small device drained my battery after a couple weeks of not using the
car. It would be unacceptable for cars to come off the production line that
way.

~~~
eck
The ADXL78 series [1] which is recommended for vehicle collision sensing draws
1.3 mA. If it were the only load, it would take on the order of ten years to
discharge a car battery, which is well below the self-discharge limitations. I
don't know if lower power sensors are available, or if some rule like "enabled
for 24 hours after the car is run" would be appropriate, but lack of power for
the sensor does not seem like a good reason for the airbags to be disabled.

Bluetooth devices actively searching for devices to pair with could plausibly
draw significantly more power than that.

[1] [http://www.analog.com/static/imported-
files/data_sheets/ADXL...](http://www.analog.com/static/imported-
files/data_sheets/ADXL78.pdf)

~~~
toomuchtodo
> if some rule like "enabled for 24 hours after the car is run" would be
> appropriate

There are pressure sensors, such as those used to determine if the passenger
airbag should be enabled/disabled. That should be the reference for both
driver and passenger; if seat = occupied, trigger airbag if collision
detected, regardless of engine status, ignition switch position, etc

If only automakers could update this sort of logic over the air...

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yason
It's kind of funny that now that everything in a car is effectively software-
controlled something like a mechanical ignition switch is still left to
control a main circuit that's so crucial it will stop the engine if broken. To
think, we do have wireless car keys already, with just a start/stop button on
the instruction panel.

Even with physical keys I would assume that this particular circuit would be
controlled via a relay and the car computer would only let the driver to stop
the engine by removing the key if the car was not moving.

~~~
moioci
In the news over the last couple of years, I've seen more than one report of
schoolchildren stopping a runaway school bus (driver passed out, etc.) by
turning off the ignition key. So this behavior can be a feature, not a bug.

~~~
yason
Turning off the engine doesn't have to be attached to the mechanical ignition
switch.

There are already cars where the ignition switch is completely wireless and
software-controlled. For example, many cars offer a start-stop feature which
turns the engine off when standing in red lights and automatically starting it
again the foot moves from brake pedal to the accelerator. People are going to
learn that there's no such thing as ignition switch anymore.

Motorcycles have red kill switches that shut down the engine completely. A
school bus or a car could have something like that.

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lando2319
"In one deposition, Mr. Cooper confronted Raymond DeGiorgio, the head switch
engineer on the Cobalt, with the differences between the original switch and
the replacement. While Mr. DeGiorgio said he saw the differences, he could not
explain why the part had been changed without a corresponding change in its
identification number."

Since the part was changed on the later models (post '06-'07) without changing
the part number, that means there is no way to tell the new ones from the old
defective ones. This goes against commonsense, why was this done?

~~~
corresation
_This goes against commonsense, why was this done?_

Almost certainly because they knew about their own enormous liability. They
settled with a family for this issue in February of 2006, and not long after
did the engineering change, albeit leaving the defect out there on millions of
cars (insert Fight Club quote).

I suspect this issue is going to continue to grow until someone is charged
with criminal negligence causing death.

~~~
joering2
> I suspect this issue is going to continue to grow until someone is charged
> with criminal negligence causing death.

Which is worth noting won't happen; not under this administration with Holter
behind DOJ's steers. Keep in mind, GM was bailed out and saved from bankruptcy
by taxpayers money, despite their uproar. Clearly, GM is in bed with
administration.

------
voidlogic
I am not saying this is the drivers fault as, based on how the facts are
presented here, is clearly GMs.

But- Are the deaths due to the drivers not adapting quickly enough to the loss
of power steering? After all breaks and steer are still working?

I have driven a vehicle without power steering and it wasn't that bad, and the
vehicles in question (Cobalts) are rather light.

~~~
jevinskie
The article stated that you also lose airbags when the ignition is not in the
run position. That seems pretty significant!

~~~
smileysteve
I think that this is the key argument fir the deaths caused. But, I was under
the impression that the effectiveness of air bags compared to their hazards
was coming into question in testing anyway. a seat belt saves many more lives
than an airbag?

~~~
josephlord
The combination is the best (apart from not crashing at all). I had heard that
US airbags were bigger than European ones as they were designed to attempt to
compensate for the lack of seat belt use (which was apparently common in the
90's).

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DiabloD3
Can we stop posting links to nytimes until they get rid of the paywall?

~~~
gojomo
NYTimes is often the best or original source for an important story.

Most readers here can either afford a subscription, or know how to read a
story-of-interest without sending paywall-triggering cookies.

Some great reporting entities, using information beyond that which we have as
readers, have decided such leaky paywalls are better than the alternatives.
Against that domain expertise, we don't need HN to adopt some uniform,
ideological "boycott all paywalls" policy. If it's so easy to get the same
good stories from elsewhere, find them and submit them.

