- The Washington Times - Thursday, October 27, 2005

These days, more and more owners are complaining about intermittent problems with their vehicles and they range all over the spectrum. Sudden window openings, power seat movements, engine shutdowns, HVAC system variations, brake boost failures, navigation system anomalies, transmission shifting glitches, remote locking system failures, windshield wipers coming on, alarms engaging and countless other operating deficiencies are reported around the country. Shop technicians seem unable to fix or even duplicate such symptoms when the vehicles are brought in for repairs.

So why is this happening? Well, according to John Hall, the main reason is that over the past 20 years the role of electronics in vehicles has moved from being “one of the band members” to being “the conductor.” Mr. Hall is a specialist in automotive electronics and has written a book called, “Semiconductor Design and Implementation Issues In Integrated Vehicle Electronics.” In the book Mr. Hall explains that electronics, specifically microprocessors, run your vehicle. Simply put, microprocessors are computers contained only a few chips and they are everywhere in our lives. There’s at least one in your microwave oven, TV, VCR, DVD, etc., and a whole bunch of them in your car.

That’s where the problem begins. Actually, the problem begins before the introduction of microprocessors into vehicles, back to the buying process itself. The manufacturers have constantly strived to develop capabilities into their vehicles that large and varied populations will embrace and, more important, pay for. They have known for decades that fewer and fewer buyers will read complicated instructions for operating all the gadgetry, so the entire thrust of development is toward automated, “idiot-proof” features and lots of them.

The answer to the manufacturers’ dilemma is the microprocessor. More to the point, it’s the Control Module. This is a central “brain” built into the vehicle and its job is to consolidate and control a variety of functions. In actuality the control module (called many different names by individual manufacturers) is a bundle of controller chips, integrated circuits and microprocessors, all integrated into a central “command” unit. Individual electronic control devices that run, for instance, the windshield wipers or a four-wheel-drive transfer case, all “talk” to the Control Module which, in turn, allows the vehicle’s electronics to handle many tasks at the same time.

Why do this, you might ask? Well, if you wanted to control each of a modern vehicle’s electrical components individually any other way you’d have to “hard wire” controls to every one of them and use a lot of switches. That would mean miles of wire and piles of other components for which there’s simply no room, not to mention weight and cost concerns.

The microprocessor-packed Control Module answers the manufacturers’ problem. It becomes the “conductor” of the vehicle’s “band,” as mentioned above. Unfortunately the solution to the problem created new opportunities for failure. One of these is the wiring that goes from the functional controllers to the module. Wire is a great transmitter of electrical current, of course, but it is also susceptible to high-voltage “spikes” from static discharges (lightning, high-voltage sources, shortwave radio, etc.) and can act like an antenna if it is not properly shielded.

Another failure mode happens when the control module’s microprocessors become overloaded with false signals from any of the controllers or sensors that are connected to it. These devices are just as susceptible to outside electrical “noise” as the microprocessor itself and it’s nearly impossible to engineer around every potential failure or error in a cost-effective way. Military equipment is incredibly expensive because it is protected from such interference, but no one could afford an automobile with the same level of sophistication.

The reason your car might do weird things — or do nothing at all — is essentially the same reason your computer might “latch up.” Lousy software design aside, computers and cars largely use Complementary-Symmetry Metal Oxide Semiconductors (CMOS) and similar devices. Any voltage surge through an input or output (we’re talking about very, very small operating voltages here, and any higher voltage signal is not tolerated) causes CMOS circuits to stop functioning until power is removed and re-applied. Once the latched-up CMOS circuits are turned off and back on, they work fine and show no evidence anything ever failed.

There are protection techniques currently in use by manufacturers to limit “stray” signals to electronic circuits. Resistors and diodes are added to circuits to filter incoming high-voltage signals and the control modules themselves are packaged in interference-shielding materials. However, vehicles have lots of wiring in them and any single wire on any day can suddenly become an antenna that is tuned precisely to some stray electromagnetic signal. Under the right circumstances a policeman’s radar gun, CB radio, microwave tower or even a customer sliding over the seat can generate a static voltage spike that results in a momentary, erratic, “false” signal to the vehicle’s control module. This can result in one of innumerable things happening, some of which are listed in the opening paragraphs, to the vehicle. (By the way, that spark you get when you touch a switch plate on a winter’s day has between 2,000 and 3,000 volts.)

The problem is that many of these symptoms can’t be traced by even the most competent technicians at the shop level, thereby leading owners to conclude that they have a “lemon.” In addition, many problems can occur after sound systems or other aftermarket electronics have been installed in vehicles because the integrity of the wiring has been compromised.

That’s why dealerships are telling customers not to install aftermarket devices that haven’t been certified by vehicle manufacturers. Eventually the state of the art in electronic design will catch up with, and solve, the potential for latch-up and false-signal failures in vehicles. Until then the best protection for consumers is to avoid cutting-edge technology features in new vehicles. Wait a few years for these devices to become reliable, mainstream features.

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