Investigations into whatever is lurking behind Toyota's crisis of quality have put a spotlight on all that can go wrong with auto electronics — the growing number of wires, sensors and computer chips that have profoundly changed the automobile in the last decade.

Though no smoking circuit has been found so far, a picture is emerging that shows the automobile industry's technology is racing ahead of quality-control testing and regulators. It's troubling not only for Toyota owners but for drivers of any modern car that's basically a computer on wheels.

Toyota insists that electronics played no role in the unintended acceleration that has sparked its massive recalls, and no one has been able to disprove it.

Lawyers, regulators, engineers and politicians aren't so sure.

The auto industry has been moving at Pentium speed since the late 1990s to replace mechanical cables and other devices with computers to control everything from brakes to throttles to power steering. Automakers say electronics have made vehicles safer with devices such as air bags and antilock brakes. It's also made cars more fuel efficient, cleaner and, usually, more reliable.

Still, things can go wrong and diagnosing problems is complicated.

Glitches can include buggy software, circuitry that's randomly influenced by electrical interference and shorts caused by microscopic "whiskers" that sprout from solder. It can be one or more of these problems, as well as environmental factors — a blast from a heater vent or moisture from the road — that can cause a failure. Age also can be a factor.

"You're looking for a needle in a haystack," said Raj Rajkumar, an electrical and computer engineering professor at Carnegie Mellon University in Pittsburgh. "Those are very hard to reproduce. The problem happens and you go back and check and it's not there. The normal tendency is to blame it on the driver and go on."

And that's what Toyota did initially.

Drivers complained their vehicles accelerated out of control — without stepping on the gas. But complaints were largely dismissed by Toyota, its dealers and government regulators, who blamed mechanical problems or drivers stepping on the wrong pedal.

Toyota, which until recently had a reputation for being high-quality and cutting-edge, began replacing mechanical accelerators with electrical ones starting with the Camry in 2002. Since the 2007 model year, all its cars have been equipped with the high-tech throttle.

more