Sudden Acceleration: A hot topic.
R. Scott King, BSME ::::
Fueled by millions of recalled Toyota vehicles, the motoring public, news media, and federal safety regulators, have not been this sensitive to the issue since the days of the “run-away” Audi’s. Now, and perhaps as part of a “lesson learned” exercise or maybe just prudent engineering, at least one manufacturer is also taking notice – and taking an important step in reducing potential sudden acceleration.
The sudden acceleration “problem” is not new; nor are the efforts to reduce its occurrence. For example, previous studies have shown that a significant portion of such claims are the result of pedal misapplication while shifting an automatic transmission out of park. As a result, manufacturers designed and installed the Brake Transmission Shift Interlock System, a system that ensures an operator’s foot is properly placed upon the brake pedal before shifting the transmission. According to some studies, such systems have been quite effective. More recently, however, sudden acceleration claims seem to center around vehicles already in motion, thus suggesting a different problem.
Many newer vehicles are equipped with electronically controlled throttle (ECT) systems. As the name suggests, there is no longer a mechanical link, such as cables and linkages, which connect the accelerator pedal with the engine. Rather, the components of an ECT system typically include accelerator pedal position sensors, throttle actuator motors, wires, and computers. Additionally, because computers are used so too are computer programs.
Toyota has acknowledged that certain of its accelerators are prone to sticking and thus may have caused at least some of the cases of alleged sudden acceleration. Others, however, speculate that the cause may be related to computer programming. To address this potential cause, General Motors, which also uses the ETC system, has announced that it will soon begin installing a new brake safety measure that will effectively turn off the power to the throttle actuator motors and return the engine to idle speed. Thus, in theory, even should an accelerator pedal stick or become entrapped under a floor mat, simply pressing on the brake pedal will de-power the engine.
Like GM, Toyota also has plans to implement this safety feature, paralleling steps already taken by other manufacturers. Federal legislation requiring its use also seems likely.Case Studies