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My Car is Full of Computers

August 3, 2013

This article has nothing to do with “My hovercraft is full of eels”, although perhaps it should.  I own a 2010 Honda Accord that I bought new.  I’m quite pleased with this car.  Until recently, I had no inkling that it was full of computers.

I got a recall notice in the mail.  It covered two problems with the car, none of which I had encountered.  One was for possible carbon accumulation in the engine.  According to the letter, if the car was operated for a long period of time in cold temperatures and for short trips, so that the engine never warmed up fully, carbon could accumulate in the engine.  The other was for possible damage to a bearing in the automatic transmission.  Apparently, if the shifter was rapidly moved from forward to reverse many times, as might happen when the car was stuck in mud or snow, this bearing could be damaged.  The letter claimed that both of these potential problems could be fixed by firmware upgrades, which they called software upgrades.  That’s when I realized that both the engine and the transmission ran under control of computers.  When I took the car in, the service manager told me that  the software upgrades should take about 1/2 hour, but they might be longer because “You know how computers are”.  I played innocent when he said that.  It took about 1/2 hour.  I was impressed.  It would have taken much longer for mechanical fixes.

I found out later that my car is full of computers, maybe a dozen of them.  Maybe there’s more than that.  They all communicate through a bus, but each computer is autonomous.  This is a good design.  Each little computer performs a specific task, managing a specific portion of the hardware on the car.  The mechanical parts can be simplified or eliminated because of this design.  I can imagine the mechanical nightmare needed to control fuel injection and valve timing on an internal combustion engine.  Computer control is a much better way to do it in this case.  It was computer control that made the last big jump in fuel economy.  Likewise, an automatic transmission used to have a complex arrangement of hydraulic valves and passages to control its operation.  These must be all gone now, replaced by a tiny computer.

Of course, relying on computers brings new risks.  I’m assuming that the electronic components are highly reliable and well tested.  The risk comes from the installation of malicious software.  This topic has been in the news recently, along with a great deal of speculative stories.  Reuters has a good summary.  Academic research is available here.  I was surprised to read that a car’s entertainment system could be used to subvert the operation of various computers within the car.  All it took was a specially-crafted disk inserted into the CD player.  Isolation is the key here.  I can’t see any reason for the entertainment system to be interconnected with the system bus in the car.  Even if the entertainment system contains a computer, it should be completely separate from the other, more critical, computers.  It’s a violation of security rules to make it that easy to introduce malicious software.

The current stories revolve around the car’s diagnostic connector.  I suppose that’s also used to perform firmware upgrades on various computer systems within the car.  Little wonder then that it could be used to take control of a car.  In this case, that level of access from the diagnostic connector is necessary for service technicians.  Unauthorized access is the problem.  Just now that has to be physical access, but I’m sure this will change in the future.  How long will it be before we start hearing about compromised computers in automobiles?

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