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General Motors Recalls 4.3 Million Vehicles Over a Software Bug (gizmodo.com)
An anonymous reader quotes a report from Gizmodo: If you own a GM vehicle from 2014-2017, listen up: General Motors is recalling nearly 4.3 million vehicles worldwide after discovering a software defect that prevents air bags from deploying during a crash. The software bug may also prevent the seat belts from locking properly. The flaw has already been linked to one death and three injuries. Vehicles affected by the recall include 2014-2016 car models of the Buick LaCross, Chevy SS, and Chevy Spark EVs. It also includes 2014-2017 models of the Buick Encore, GMC Sierra, Chevy Corvette, Chevy Trax, Chevy Caprice, Chevy Silverado. Additionally, the recall affects 2015-2017 models of the Chevy Tahoe, Chevy Silverado HD, Chevy Suburban, GMC Yukon, GMC Yukon XL, GMC Sierra HD, Cadillac Escalade, and Cadillac Escalade ESV. GM will notify owners of affected vehicles and update the software for free, according to the NHTSA. "In the affected vehicles, certain driving conditions may cause the air bag sensing and diagnostic module (SDM) software to activate a diagnostic test," the National Highway Traffic Safety Administration (NHTSA) said in a statement. "During the test, deployment of the frontal air bags and the seat belt pretensioners would not occur in the event of a crash."
After knowing a number of owners both former and present, I have come to the conclusion that these vehicles are somehow designed to "expire" after a while.
Could this be the reason one doesn't see many of them manufactured over the last 15 years?I will never forget one Cadillac I found in the shop with a malfunctioning transmission at exactly 100,801 miles with a 100,000 mile warranty. For me, GM is a no!
The old fashioned method was airbags used to be triggered by a magnetic ball embedded in a 'cup' that on the application of severe deceleration, the ball popped out, closed a circuit and triggered the airbag. The same goes for seat-belts. A rotating wheel that trip and engages a cog on the application of a set amount of acceleration.
Isn't some simple mechanical fuse / switch sufficient for the airbag deployment system? Also, did old cars require SDM for the seatbelt to lock properly? Why are they changing mechanisms that have proved themselves?
Isn't a carburettor and magneto sufficient to run an engine? The answer is yes, if you have no regulations, reliability and/or liability to be concerned with.
Air bag systems have had software for literally decades, it's not new. Seatbelts still have mechanical locking. Electronically-controlled pre-tensioning is something else that has been around for decades now, and is part of the airbag control system.
Modern air bags have variable deployment energy, which requires determining the severity of the collision, the weight of the occupant, etc. There are also side curtain and many other types of airbag that should only deploy when required, so the pitch, roll, and yaw, and even sideslip of the vehicle has to be known. Side curtain airbags need to deploy before the vehicle lands on its side, so software is required to predict when impact is likely to occur.
Also, electromechanical systems can't self-check and diagnose themselves when there is a system failure. Air bag systems continuously monitor even the resistance of the igniter in the airbag to make sure it is correct.
As vehicle manufacturers found out with carburettors and emissions regulations, mechanical systems quickly become too complex and unreliable to react to many inputs. There is no new passenger vehicle sold in North America that doesn't run its engine entirely from a computer. It's just that superior. Likewise with airbags.