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Age Takes Its Toll on Car's Electronic Hardware


Not many people use computers that are 8, 9, even 10 years old, unless it's the one under the hood of their car.

Most personal computers, cell phones and other gizmos that help drain the family budget typically end up on the junk heap after about five years. But the lowly powertrain control module--the brains of modern cars--has to chug out its bits and bytes for up to 15 years.

And many car owners are finding that, as their highly automated cars age, the electronic systems are subject to the same sort of decay processes that affect the paint and sheet metal. After many years, they aren't as spiffy as the day they left the factory.

Consider the plight of R.C., who wrote to Your Wheels about his wife's 1993 Mercedes-Benz 190E. It often sputters and dies at traffic stops, and he wonders what the problem could be.

With so little information, even the best mechanic could only guess. But as with a lot of aging cars, deteriorating electronics under the hood are likely to be playing at least some role in the engine misfiring.

Let's start with the electronic hardware. Newer cars have up to 80 microprocessors that must endure conditions similar to those in the Defense Department specs for combat equipment.

Microprocessors in the passenger compartment must operate in a temperature range of roughly minus 35 degrees to 136 degrees. That's good to know on a cold night in North Dakota or a hot day in the Mojave Desert.

Electronic devices mounted on the engine must withstand blazing temperatures of about 230 degrees--enough to fry the stuff inside a desktop computer.

And auto engineers are aiming to substitute electronics for a transmission's hydraulic control body, said Delphi Automotive engineers Norm Swanson and Bill Whitlock. That calls for placing microprocessors inside the transmission where they will be bathed in transmission fluid. That's a chemically nasty environment that's even hotter than the exterior of the engine.

All of these electronic components are supposed to hold up for at least 10 years or 150,000 miles, according to auto industry specifications.

Obviously, many people own and drive cars longer than that. The average car on the road is more than 8 years old, and many cars typically log more than 200,000 miles before owners give up on them. So it's not surprising that plenty of sensors and microprocessors need to be replaced, starting typically after a car is 5 years old.

Software doesn't degrade, but more and more auto makers are finding glitches or a need to improve the original software.

"Certainly the software we write for critical systems, such as the engine management and safety devices, has to be very robust," said John Sinelli, an automotive electronics designer at Visteon. "You can't allow them to default to an operator reset."

That essentially would require installing a reboot button on the dashboard, something almost no motorist would accept. After all, who wants to have to reboot the air-bag computer in the middle of an accident? To avoid that, the auto industry depends on extensive testing of critical software.

"As the systems get more complex, the tools have gotten more sophisticated," Sinelli said. "It greatly minimizes . . . errors. But it is the nature of the business: There are software errors."

The industry has developed diagnostic tools for dealerships to "flash" new programming into a car's powertrain control module when software errors are uncovered (as discussed in a recent Your Wheels column).

The advent of software contained in programmable memory is a relatively new phenomenon. How the practice of installing new programming in old modules will work in 10 years, when owners of vehicles typically go to independent garages for service, is unclear.

But many experts say the industry has been gaining experience for more than a decade in sorting out hardware and software problems.

"I think we're going to be seeing fewer problems . . . because of the experience," said Jerry Goss, content manager at Alldata, an automotive repair publishing company.


Ralph Vartabedian cannot answer mail personally but responds in this column to automotive questions of general interest. Please do not telephone. Write to Your Wheels, Business Section, Los Angeles Times, 202 W. 1st St., Los Angeles, CA 90012. E-mail:

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