Posts Tagged ‘control’

Sudden Acceleration Problem May Not Be Limited To Toyota Vehicles

8 million Toyota vehicles have been recalled due to issues relating to the gas pedal, as mentioned in CNNMoney today. Dr. David Gilbert of Southern Illinois University appeared on ABCNews demonstrating how, he claims, accelerator pedal units on certain Toyota vehicles are failing. Toyota mentioned in their Statement on Rebuttal of Professor Gilbert’s ‘Unintended Acceleration’ Demonstration

that he has reengineered and rewired the signals from the accelerator pedal. This rewired circuit is highly unlikely to occur naturally and can only be contrived in a laboratory. There is no evidence to suggest that this highly unlikely scenario has ever occurred in the real world. As shown in the Exponent and Toyota evaluations, with such artificial modifications, similar results can be obtained in other vehicles.

More popularly, however, are the problems with Toyota vehicles in which the accelerator pedal becomes trapped in the open-throttle position by an unnecessarily heavy floor mat. This seems to be the biggest cause for concern, as several documented cases of this happening have been recorded. Another issue, and reason for recall, has been caused by friction devices in the accelerator pedal unit wearing down and causing the pedal to stick, possibly in the partially open throttle position.

In Dr. Gilbert’s demonstration he basically “hacked” the throttle sending unit to make the powertrain control computer “think” that the pedal was being pressed to the floor. Previously, in mechanical throttle systems, a cable connected the pedal to the throttle plate, which was held closed by a spring. If the throttle cable broke, the plate would close due to the mechanical force of the spring. This demonstration would basically be the equivalent of cutting that cable, and pulling on the end that was still connected to the throttle plate. I guess if somebody decided to try and rewire their gas pedal, this type of event may occur. But naturally, I don’t think so.

Fully electronic throttle control units have been integrated in vehicles for some time now and are commonplace in almost all new vehicles produced today. This was something that we knew was eventually going to be an issue, and it’s certainly not limited to Toyota vehicles. This situation could occur in any vehicle utilizing an electronic throttle control unit. Now I’m not aware of any documented cases of these units failing in the manner that Dr. Gilbert demonstrated, and if anybody is, please reply to this post in the comments section with a link as proof. I have to admit that I am a little iffy about vehicles driving themselves, but as long as automakers continue to design the systems properly, and you keep any malicious electricians away from your gas pedal, I don’t think we really need to worry about it.