A series of mass recalls at Toyota Motor has raised questions about potential problems with the computer systems running cars today and led US safety officials to launch a new probe into possible electronic interference.
The Japanese automaker insists that there are no problems with the electronics in its vehicles and that there are relatively simple mechanical reasons why millions of vehicles were recalled to address problems with sudden, unintended acceleration.
Toyota executives said Monday they were convinced that sticky pedals and stuck floor mats were at the root of the problem, and had subjected the computer systems in their car to rigorous and extensive testing.
But they have not yet determined why their popular Prius hybrid has experienced problems with its braking system.
Ford on Thursday announced that it would be upgrading the software in the brake systems of two of its hybrid models because of problems experienced when the vehicles switched from "regenerative" to "conventional" braking.
And experts say that the Prius problems are likely also a software problem.
"In my view, it's poor execution in the coordination between the regenerative brake and the friction brake," said Huei Peng, a mechanical engineering professor at the University of Michigan who studies automotive systems.
Hybrids rely upon the "regenerative" braking system to generate power for their electric battery. But since that system cannot function on its own, it has to work in tandem with a conventional braking system.
"For this system to work it's a real coordination issue," Peng explained.
"It's possible that in this case somehow the (software) tuning wasn't done perfectly right."
But while all computerized systems lend themselves to software errors or bugs, Peng said vehicles are much safer with them than without.
"I think there may be even more accidents if we go back to mechanical brakes," he told AFP.
"On ice and snow, I don't think humans handle better than the electronic systems. Can you imagine giving up anti-lock brakes?"
The average vehicle has anywhere from 30 to 70 central processing units or embedded controllers, Peng said.
They handle everything from windshield wipers and lights to computing how much pressure should be placed on the brakes to stop a vehicle safely given current weight and road conditions.
"Definitely they do have bugs in these control units in cars," he said.
Most of them are not serious, and dealers will diagnose and fix them for free without even bothering to tell their customers.
Another concern is the possibility that electromagnetic interference - like the buzz heard in speakers if a cell phone gets too close - could be interfering with the computerized controls in cars.
Some critics have speculated that this interference with electronic throttle control systems could cause unintended acceleration, and that Toyota needs to take another look at its software.
"It really appears that there is a problem with the electronics," Joan Claybrook, who used to head the US National Highway Traffic Safety Administration, told the Washington Post.
"There have been incidents of acceleration when the floor mats were already taken out," she said of the complaints registered against Toyota vehicles.
The NHSTA - which has already studied the issue extensively - on Wednesday said it was going to take a "fresh look" at both electronic throttle control and the possible effects of electromagnetic interference.
"This is not a defect investigation, because the agency has no reason at this point to believe there are safety defects in these systems or in their ability to function when exposed to EMI," the safety agency said.
"Instead, this is a background examination of the underlying technological issue."
While it's important to examine the issue, the concerns about electronic interference are overblown, said David Champion, director of automobile testing for Consumer Reports magazine.
"Most cars that are sold today have electric throttles that we don't see any problems with," he said in a telephone interview.
"And even the Toyota ones with unintended acceleration, NHTSA has done a lot of testing these electronic throttles with the equivalent of 20 cell phones in the cars, huge magnets and various other things to try to cause problems and could not ever reproduce a stuck throttle position."
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