6 ms·

An Engineer’s Eureka Moment With a G.M. Flaw

43 points by wallflower 13y ago

tsomctl 13y ago
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).
- barrkel 13y ago
  Electric arc welding can fry the electrics (think ECU etc) on a vehicle if you don't disconnect the battery. Airbags would be at the lower end of your concerns.
  - msandford 13y ago
    It's actually better to disconnect the ECU entirely if you can. There is a large wiring harness that brings 40+ wires together into one or a couple of plugs which you can undo in a few seconds. Plenty of ECUs have been ruined by folks getting their exhaust welded when the people doing the welding don't really know what they're doing. Especially if they normally work on older cars which tend not to have sensitive electronics.
  - deleted 13y ago
    [deleted]
- Zigurd 13y ago
  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.
  - raverbashing 13y ago
    I don't think any car lasts more than a couple of weeks without being turned on, OBDII bluetooth dongle or not For the airbag I think the sensors are passive, but even if they aren't, a grace period could be added (like, it will shut down after someone shuts off the car, then opens and closes the door)
    - dippyskoodlez 13y ago
      You have a problem if yours does not.
      - anonbanker 13y ago
        Often, the problem can be summed up as "Canada is below zero for months at a time."
  - eck 13y ago
    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/ADXL78.pdf http://www.analog.com/static/imported-files/data_sheets/ADXL...
    - 13y ago
voidlogic 13y ago
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.
- msandford 13y ago
  A power steering rack & pinion is rather different than a manual rack & pinion. In my experience when a car loses power steering it's a real pain. Especially if you're used to power steering. Having it drop out could feel like the steering wheel has locked up.
- albeec13 13y ago
  I was wondering the same thing. As a teen I drove a small car, and at least once or twice while playing around with shifting gears (mind you, this was an automatic) I accidentally shifted into reverse while in motion, causing everything in the car, including the engine and power steering to shut down. All I did was quickly turn the ignition key to restart the engine and all was well. Yes power steering loss makes the car very sluggish, but really you're just coasting at that point and turning the ignition switch quickly is second nature. I'm sure it could be a little more frantic at highway speeds. I wonder if this is something that should be taught in driver's ed? (Regardless of my above comments, I do agree GM is responsible for sweeping this under the rug)
- klinquist 13y ago
  Steering as long as you are moving isn't too bad. With brakes, you've generally got one solid push of the pedal (vacuum reserve in the booster) before you have to stomp VERY hard to get a vehicle to stop.
- logicallee 13y ago
  "Due" and "because of" are very difficult questions. Someone whose family member died but who has a bigger beef might well conclude, "because he didn't get the bonus that [some company] owed him, he ended up having to settle for a Chevy Cobalt - a car that likely ended up killing him." Is this use of "because" correct? Sure, why not. He wouldn't have died if his bonus had been paid? Might well be true. I would personally not be interested in "due to" and "because of". To answer your question, you could have asked instead, "I wonder if experienced drivers who were used to driving without power steering would have not been adversely affected." Note: my example is a case where blaming a lack of bonus on the death is clearly wrong - but isn't attributing causative power to someone not being used to a car suddenly changing into a totally different input paradigm equally wrong? Better to stick to the factual question for starters.
DiabloD3 13y ago
Can we stop posting links to nytimes until they get rid of the paywall?
- morgante 13y ago
  Just Google the article to bypass the paywall.
- fla 13y ago
  Funnly, the paywall did not appear on my iPad.
- eCa 13y ago
  You can read it in an incognito/private window.
- gojomo 13y ago
  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.
- mhb 13y ago
  Don't you think it's worth paying for good content?
lando2319 13y ago
"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?
- tlrobinson 13y ago
  It seems like either they thought the change was insignificant, or they were trying to hide the fact that it was defective.
- corresation 13y ago
  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 13y ago
    > 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.
- PhantomGremlin 13y ago
  This goes against commonsense, why was this done? Others have speculated it was done for liability reasons, that's IMO the most likely explanation. The beauty of civil litigation is there's an easily accessible paper trail. It would be interesting to see whether or not GM has a habit of changing designs without changing part numbers. However, frequently designs get changed by "marketing" without a part number change, even in situations without possible liability. E.g. wireless routers are sometimes totally revised while retaining the same part number. Apple also likes to implement stealth changes. Most engineers understand "commonsense", most marketing pukes don't.
yason 13y ago
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 13y ago
  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 13y ago
    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.
- Mister_Snuggles 13y ago
  It really depends on the car. My car, for example, is a Chrysler 300 and there is no real connection between the key and what provides power to the engine. Here[1] is a diagram showing how the CAN bus works on the Chrysler/Dodge LX platform vehicles. The SCM/SKREEM module on that diagram is where the ignition switch and logic that talks to the keyfob is and makes sure you have a valid key. Here's a recall related to the module which hints a little bit about what it is and does[3]. Note on the recall that this applies to a whole bunch of Dodge/Chrysler platforms. Based on the wiring diagram[2] (for Dodge trucks, which is one of the platforms that [3] applies to), the SCM/SKREEM (called Node-Wireless Ignition in one diagram and WCM in another) uses a 2-wire CAN bus for its communication. Once the SCM/SKREEM validates the key it sends a message on the CAN bus to the engine controller to tell it to start the engine. In these vehicles, whether the engine is on or off is purely under software control. That said, I'm not going to try turning my car off while I'm driving. [1] http://the8thlayerof.net/2013/11/10/canbus-vehicle-network-data-capture-tapping-the-can-network-wires-chrysler-lx-platform-2006-dodge-charger-srt8/ http://the8thlayerof.net/2013/11/10/canbus-vehicle-network-d... [2] http://tucrrc.utulsa.edu/DodgeCAN.html http://tucrrc.utulsa.edu/DodgeCAN.html [3] http://project-jk.com/images/tsb/TSB_08-007-08.pdf http://project-jk.com/images/tsb/TSB_08-007-08.pdf

43 points by wallflower 13y ago

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).

barrkel 13y ago
Electric arc welding can fry the electrics (think ECU etc) on a vehicle if you don't disconnect the battery. Airbags would be at the lower end of your concerns.
- msandford 13y ago
  It's actually better to disconnect the ECU entirely if you can. There is a large wiring harness that brings 40+ wires together into one or a couple of plugs which you can undo in a few seconds. Plenty of ECUs have been ruined by folks getting their exhaust welded when the people doing the welding don't really know what they're doing. Especially if they normally work on older cars which tend not to have sensitive electronics.
- deleted 13y ago
  [deleted]
Zigurd 13y ago
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.
- raverbashing 13y ago
  I don't think any car lasts more than a couple of weeks without being turned on, OBDII bluetooth dongle or not For the airbag I think the sensors are passive, but even if they aren't, a grace period could be added (like, it will shut down after someone shuts off the car, then opens and closes the door)
  - dippyskoodlez 13y ago
    You have a problem if yours does not.
    - anonbanker 13y ago
      Often, the problem can be summed up as "Canada is below zero for months at a time."
- eck 13y ago
  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/ADXL78.pdf http://www.analog.com/static/imported-files/data_sheets/ADXL...
  - 13y ago

voidlogic 13y ago

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.

msandford 13y ago
A power steering rack & pinion is rather different than a manual rack & pinion. In my experience when a car loses power steering it's a real pain. Especially if you're used to power steering. Having it drop out could feel like the steering wheel has locked up.
albeec13 13y ago
I was wondering the same thing. As a teen I drove a small car, and at least once or twice while playing around with shifting gears (mind you, this was an automatic) I accidentally shifted into reverse while in motion, causing everything in the car, including the engine and power steering to shut down. All I did was quickly turn the ignition key to restart the engine and all was well. Yes power steering loss makes the car very sluggish, but really you're just coasting at that point and turning the ignition switch quickly is second nature. I'm sure it could be a little more frantic at highway speeds. I wonder if this is something that should be taught in driver's ed? (Regardless of my above comments, I do agree GM is responsible for sweeping this under the rug)
klinquist 13y ago
Steering as long as you are moving isn't too bad. With brakes, you've generally got one solid push of the pedal (vacuum reserve in the booster) before you have to stomp VERY hard to get a vehicle to stop.
logicallee 13y ago
"Due" and "because of" are very difficult questions. Someone whose family member died but who has a bigger beef might well conclude, "because he didn't get the bonus that [some company] owed him, he ended up having to settle for a Chevy Cobalt - a car that likely ended up killing him." Is this use of "because" correct? Sure, why not. He wouldn't have died if his bonus had been paid? Might well be true. I would personally not be interested in "due to" and "because of". To answer your question, you could have asked instead, "I wonder if experienced drivers who were used to driving without power steering would have not been adversely affected." Note: my example is a case where blaming a lack of bonus on the death is clearly wrong - but isn't attributing causative power to someone not being used to a car suddenly changing into a totally different input paradigm equally wrong? Better to stick to the factual question for starters.

DiabloD3 13y ago

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

morgante 13y ago
Just Google the article to bypass the paywall.
fla 13y ago
Funnly, the paywall did not appear on my iPad.
eCa 13y ago
You can read it in an incognito/private window.
gojomo 13y ago
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.
mhb 13y ago
Don't you think it's worth paying for good content?

lando2319 13y ago

"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?

tlrobinson 13y ago
It seems like either they thought the change was insignificant, or they were trying to hide the fact that it was defective.
corresation 13y ago
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 13y ago
  > 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.
PhantomGremlin 13y ago
This goes against commonsense, why was this done? Others have speculated it was done for liability reasons, that's IMO the most likely explanation. The beauty of civil litigation is there's an easily accessible paper trail. It would be interesting to see whether or not GM has a habit of changing designs without changing part numbers. However, frequently designs get changed by "marketing" without a part number change, even in situations without possible liability. E.g. wireless routers are sometimes totally revised while retaining the same part number. Apple also likes to implement stealth changes. Most engineers understand "commonsense", most marketing pukes don't.

yason 13y ago

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 13y ago
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 13y ago
  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.
Mister_Snuggles 13y ago
It really depends on the car. My car, for example, is a Chrysler 300 and there is no real connection between the key and what provides power to the engine. Here[1] is a diagram showing how the CAN bus works on the Chrysler/Dodge LX platform vehicles. The SCM/SKREEM module on that diagram is where the ignition switch and logic that talks to the keyfob is and makes sure you have a valid key. Here's a recall related to the module which hints a little bit about what it is and does[3]. Note on the recall that this applies to a whole bunch of Dodge/Chrysler platforms. Based on the wiring diagram[2] (for Dodge trucks, which is one of the platforms that [3] applies to), the SCM/SKREEM (called Node-Wireless Ignition in one diagram and WCM in another) uses a 2-wire CAN bus for its communication. Once the SCM/SKREEM validates the key it sends a message on the CAN bus to the engine controller to tell it to start the engine. In these vehicles, whether the engine is on or off is purely under software control. That said, I'm not going to try turning my car off while I'm driving. [1] http://the8thlayerof.net/2013/11/10/canbus-vehicle-network-data-capture-tapping-the-can-network-wires-chrysler-lx-platform-2006-dodge-charger-srt8/ http://the8thlayerof.net/2013/11/10/canbus-vehicle-network-d... [2] http://tucrrc.utulsa.edu/DodgeCAN.html http://tucrrc.utulsa.edu/DodgeCAN.html [3] http://project-jk.com/images/tsb/TSB_08-007-08.pdf http://project-jk.com/images/tsb/TSB_08-007-08.pdf