Automakers' reliance on electronics has risks

NEW YORK–Your most expensive piece of electronics probably is not your flat-panel TV or your computer. More likely, it's your car, which can pack 50 microprocessors to control everything from the fuel mix to the rear-view mirrors.

The recalls and other technical problems besetting Toyota in the past few weeks highlight the risks of relying on electronics instead of the mechanical rods and cables that controlled vehicles for most of the 20th century.

Such advancements bring many benefits but the worry is that the car is a computer on wheels that could freeze up and potentially crash. No less a computer celebrity than Apple Inc. co-founder Steve Wozniak has said his Toyota Prius sometimes accelerates on its own.

For many years, a car's gas and brake pedals were connected directly to the throttle and the brake assembly. Now computers and electronic sensors govern many of those functions, as well as a vehicle's exhaust system, its inside temperature and a host of other operations.

Those design changes were reviewed this week when the U.S. National Highway Traffic Safety Administration began looking into 124 reports from consumers that their Toyota Priuses momentarily lost braking ability while travelling over uneven roads, potholes or bumps. Four of the reports involved crashes. The Prius problem is part of a broader issue for Toyota. Accelerators in its nonhybrid cars can get trapped under floor mats, or become stuck on their own, and fail to return to the idle position. Toyota has recalled eight top-selling models, involving 2.3 million cars in the U.S. alone and reports Sunday said the top-selling Prius will be recalled in Japan.

The wider problems appear to be conventional mechanical issues. But U.S. Transportation Secretary Ray LaHood said his department would do a broad review of whether vehicle engines could be disrupted by electromagnetic interference from power lines or other sources.

In the Prius, in addition to traditional hydraulic brakes, the car has an electronically operated braking system to recover some of the energy lost as the car slows. Some of that energy is sent to the battery that powers the Prius' electric motor. The hybrid design saves fuel and reduces emissions but it increases the complexity of the car and the number of potential failures.

One explanation Toyota has offered for the Prius problems is that there's a time lag when the Prius switches between its gas engine and the electric motor. The car would be delayed, then, in switching between the traditional hydraulic brakes and the electronic braking system.

Even if there's a momentary lapse of the brakes, they will work if the driver keeps pushing the pedal, the company has said.

On Thursday, Toyota instead pointed to the antilock braking system. Antilock brakes engage and disengage many times per second to prevent skidding. The company said it changed settings on the assembly line to prevent "inconsistent brake feel during slow and steady application of brakes on rough or slick road surfaces.''

It has not recalled cars for that change.

The first computer-controlled antilock braking system for cars was introduced in 1971. Yet the technology's complexities still can trip up manufacturers: 39,000 trucks and tractors and 6,000 school buses were recalled in 2000 to fix problems with the software on brakes made by Bendix Corp.

Today's cars are far safer and more reliable than those manufactured without electronic controls, said Bruce Belzowski, assistant research scientist at the University of Michigan Transportation Research Institute. He stressed the added complexity demands much more testing in different conditions.

In 2005, Toyota announced a recall of 160,000 Priuses following reports that brake lights lit up for no reason and gasoline engines shut down of their own accord. The culprit was the software controlling critical car functions.

Software also appears to be to blame at Ford Motor Co., which last week said it plans to fix 17,600 Mercury Milan and Ford Fusion gas-electric hybrids because of a glitch that can give drivers the impression the brakes have failed.

Ford says the problem occurs in the transition between two braking systems and, at no time, are drivers without brakes. Spokesman Said Deep says the firm will ask owners to bring vehicles in for a software fix that changes the pedal feel.

Jake Fisher, automotive engineer for Consumer Reports magazine, criticized the push-button ignition of some Toyotas and Lexuses.

To turn the engine off in an emergency, Toyota and Lexus drivers must hold the button for three seconds. Drivers of other makes, such as Cadillac, Nissan and Infiniti shut off engines by pushing the start button more than once. Fisher says a driver in an emergency might not think to hold the button and, instead, may push it several times.

An easier way to turn off the engine might have prevented a runaway Lexus accident last summer that killed four people. The gas pedal got stuck under a floormat.

Dennis Virag, president of the Automotive Consulting Group, said Toyota has erred in not adopting a brake-override system for all its cars that shuts off the fuel supply to the engine if brakes are engaged and the accelerator is down.

Most other carmakers have such systems. They save lives even when a gas pedal is working properly because there are many cases of confused drivers stepping on brake and gas pedals at the same time.

Toronto Star