Condition Based Maintenance For Automotive Systems

Modern cars have dozens of embedded systems – from adjusting the air/fuel mixture to preventing the brakes from locking – it seems nearly everything in the car is controller by embedded software.

This folks, is a revolution.  For a hundred years the automotive industry struggled to beat mechanical complexity into submission.  As progress was gradually made the demands on drivers became progressively less.  Early drivers had to be tinkerers with a toolkit and mechanical aptitude.  Today blissfully ignorant people get in their car, turn the key, and drive away.

Aside –

I once had a dog that would return from a summer walk, sit in front of an air conditioner floor vent, and periodically paw it.  Evidently he was rewarded often enough for his pawing that he came to believe he could control, or at least influence, the air conditioner gods.  Of course there was a random delay before the cool breeze started.  One could only wonder if his primitive cocker spaniel brain attributed this to the air conditioner gods being busy or perhaps angry with him.

There are times when all of us are cocker spaniels (but maybe not as cute).  In a sense, we are all cocker spaniel brained when confronted with befuddling new technology.  Indeed, Arthur C. Clarke pointed out “Any sufficiently advanced technology is indistinguishable from magic”.

To distill my thinking, we have a ubiquitous device – the car, of historic complexity, recently imbued with sophisticated embedded artificial intelligence.  Few who drive these cars understand the magic by which they operate.  Fewer still understand the limitations of that magic.  Worse, we cannot ignore the marketing and corporate agendas being applied to this unholy muddle.

For example, the people who want to sell you more oil tell you to change it every 3,000 miles while the people who want to sell you another car say an oil change every 7,500 or even 15,000 miles is fine.  Hummmmm.

Now we have all the ingredients for a real mess:

  • Complex and at times unproven technology
  • Multiple competing corporate agendas
  • Large population of uninformed users
  • Deep seated (and unwarranted) faith in magic
  • An abundance of cocker spaniel brains

A friend of mine has a fairly new car that displays a wrench icon on the dashboard when it is time for maintenance.  In the old days, a conscientious person would look at their odometer and make a service appointment at certain well-known mileage milestones.  15,000 and 30,000 miles are two examples of this traditional approach.  More recently, manufacturers have been making forays into Condition Based Maintenance (CBM).  This is cool stuff.  The idea behind CBM is that the need for maintenance depends on how hard you use something.  Embedded software in my friend’s car monitors sensors and calculates when to light up the wrench.  This is really cool until the cocker spaniels get involved.

Someone offered to change my friend’s oil around 9 or 10,000 miles.  Specific details are a little hazy.  Nobody is sure how much oil was used.  Nobody is sure if any computations or sensors were reset.  At around 15,000 miles my friend contacted the dealership to make a service appointment.  The service center representative asked if the wrench was visible on the dashboard.  It was not and the representative said not to bring the car in until the wrench was visible.  Questioned further, the representative said the wrench could not be confused by any out of cycle oil changes.  It knew when service was needed and don’t worry about bringing the car in until the wrench appears.

Note:  subsequent events and discussions with this dealership resulted in a complete retraction of this.  Evidently there is some sort of mileage based maintenance schedule.  It’s not my car and I’m not really clear on the details.  If you have a wrench on your dash – you should become knowledgeable about this.

Fast forward a couple thousand miles.  Still no wrench, but the oil warning light started coming on – first on hills, then most of the time.  Finally my friend decided to check the oil.  SURPRISE!  The engine oil was more than a quart low.  DOUBLE SURPRISE!  Hot transmission fluid barely touched the bottom of the dipstick.  We are not really sure what the wrench monitors, but clearly it doesn’t monitor fluid levels.  We’ve since learned it also does not monitor clogged air filters.  What exactly does the wrench monitor and why was it confused?  Good questions.

Now, remember – there is no real agreement among knowledgeable individuals and corporations on when you should change your oil.  3K, 5K, 7.5K, 15K…  Genuine oil change estimates are all over the map.  Given this, why would you:

  1. spend a penny in development
  2. add complexity to the manufacturing process
  3. confuse customers and service personnel

to tell someone to change their oil at 7,735 miles instead of 7,500?  This smells badly of marketing, not engineering.

Conditioned Based Maintenance is cool stuff and an excellent field for further research.  Unfortunately, its current use in cars seems badly mired in corporate politics and marketing rather than science.