Sudden acceleration in autos - not just Toyota



I’ve been intrigued by the recent reports that the problem of sudden acceleration is not limited to Toyotas. Since some have suggested problem with software code it suggests that they may share a common bug. If so, it would either be a matter of a common operating system, a common bit of shared code, or it has been introduced through some outside source Is if feasible to consider that if the last, it is introduced through the devices that plug in to read the car’s computer logs?


I seriously doubt there’s one bit of shared code.


That’s a great theory, but I don’t think auto makers share their computer programs with each other. There are many possible causes for sudden acceleration. Finding a common link between different brands may prove difficult.


Ever heard the saying “there’s only so many ways you can slice an egg”?

If you put a half dozen, capable engineers into a clean room environment and gave them this fairly simple control problem (with all the normal constraints of a car design), they would likely emerge with nearly identical designs.

Now imagine a serial development environment where the subsequent developers have access to the competitor’s design(s). They are going to reverse engineer them, take the good points and build upon that.

So, in the end, the systems will be pretty similar in their most basic architecture.

We could engage in a rather lengthy discussion regarding robustness of design versus risk analysis versus cost but suffice it to say, there is a balance that is struck between those such that you have a viable design.

I seriously doubt that they have invested the necessary resources to ensure that the system is free from all possible error modes. Simulation only goes so far and empirical testing is limited by the desire to launch a new system as quickly as possible. There are bound to be bugs in their designs. Guess who’s doing the final V&V?


I strongly suspect that in some cases the common link is operator error.


The only thing uncommon here is the death caused by Toyota’s unintended acceleration. They refuse to admit that even a possible cause may be the electronics or software. Listen to Mr. Toyoda testify at the congressional hearings. Listen to the witness that said putting the car in neutral did not help. I doubt they share code with other manufacturers. That notion is silly, and a desperate attempt by Toyota apologists to obfuscate the issue.


When the shifter is placed in the neutral position, and the trans doesen’t go to neutral, what could be happening here? Does it have anything to do with high rpm?


Error meaning buying a Toyota?


Some cars, such as the suspect Toyotas, do not have a mechanical linkage between the shift lever and the tranmission. An electronic control module senses where the shift lever is and actually shifts the tranmission electronically. Same process with the accelerator. No mechanical linkage. So if you experience a software bug problem or an electronics problem interfering with that process, the only option may be to KYAG.


Someone posted in another thread that if all else fails, you can turn the engine off. They said it was safe to do so because the ignition can’t be locked unless the car is in park. Power steering is not needed except at very slow speeds, so there would be enough control to pull off the road. Brakes are power assisted, so braking would be possible too.


There is no key to turn. You push a button to turn the engine off. Electronic signal being sent. No mechanical contacts. Survivors have testified in the congressional hearings, for instance, that trying to turn off the engine, shift into neutral, take your foot off the accelerator, etc. have had no response from the car. Or at least no desired response.


This car has performed an illegal operation and cannot be shut down, want details?

Error code: 0x928364758969473562352


I’m going to post this comment that I already left in another forum, as it may simplify things for those that don’t understand how computer software works. It is purely hypothetical and does oversimplify some things, and I’ve cleaned it up somewhat since the previous post:

I think the problem is a bug in Toyota’s engine management software that only emerges in very rare conditions. Such as if on your computer, you were using an office program, then decided to do some odd combination like CTRL+ALT+F12, after copying data to the clipboard twice, then when you pasted the data, you got something entirely different. Only 1 in 100,000 people may perform this combination of actions, and it may not affect the software every single time—lets say only if your email was open at the same time.

This is only an example, but when you have several pieces of software that are interacting on some level with each other, in millions upon millions of lines of code, you can’t always test for every bug–it’s just impossible.

Now transplant that example to your Toyota. You’ve been cruising at 65 MPH exactly, the defrost is on, causing the AC to run. You’ve just tapped the brakes because someone almost cut you off. Let’s say the engine management system had decided that your extended 65 MPH cruise was a good time to open the EGR or do some other emissions-related event because you wouldn’t normally notice it at cruise speed, but the AC being on adds some unusual data to the program. Now you tap the brakes but still resume cruising… The emission control subroutine tries to stop the EGR event, but a software bug instead crashes that part of the program, and the data from the brake input or leftover from the EGR event gets put somewhere in memory it was never intended… in this case in the memory location or register that indicates the throttle position, overriding any input from the actual accelerator. Suddenly your car takes off like it has a mind of its own! You could consider this a “cascade failure”, where no one event causes a problem, but unrelated events working randomly together can cause a catastrophe.

Eventually some “sanity” check in the software compares the throttle with the memory and decides they disagree, or the software recovers from the error and finally starts “polling” the accelerator input again. So the unintended acceleration event is now over. But due to an exception like this never being planned for, the computer doesn’t know it should write the erroneous event to a log or turn on the ‘check engine’ light.

A similar chain of events to my fictitious example is what I think Toyota will eventually find in examining their software. It may be that similar oddities exist in other manufacturers’ software, but they have one more level of sanity checking (like BMW, Chrysler, Nissan, etc. overriding the throttle when you hit the brake) or just whatever bugs they have end up causing something mildly weird, like your engine fan to run for a few seconds, not potentially dangerous like unintended acceleration.