My Theory on Toyota's Unintended Acceleration Problem

Re: My Theory on Toyota's Unintended Acceleration Problem - MORE

UPDATE TO ALL:

Prompted by something I read just now in one of the postings, I searched the NHTSA website and found that NHTSA ODI has opened an investigation into the 2004, 2005, 2006, 2007 and 2008 Priuses for "VEHICLE SPEED CONTROL:ACCELERATOR PEDAL" i.e. unintended vehicle acceleration. This investigation was opened across the board on ALL of these models on Feb. 16, 2010, almost a month ago.

Note what I also found linked to these open investigations (THIS IS VERBATIM):

"NHTSA IS SEEKING INFORMATION ABOUT HOW TOYOTA VIEWED COMPLAINTS AND OTHER REPORTS TO TOYOTA AND HOW TOYOTA ASSESSED POTENTIAL ELECTROMAGNETIC INTERFERENCE. THE AGENCY ALSO REQUIRES INFORMATION FROM TOYOTA ON WHY SOME MODELS OF VEHICLES WITH ELECTRONIC THROTTLE CONTROL WERE NOT INCLUDED IN THE RECALLS. THIS INVESTIGATION DOES NOT DUPLICATE TQ10-001 OR TQ10-002."

*********************

I HAD NOT SEEN THIS INFO BEFORE TODAY. I CAME UP WITH MY THEORY ON MY OWN AFTER REVIEWING THE BENTLEY TECH MANUAL THIS WEEK. You can draw your own conclusions.

 

Not to put too fine a point on this, but it was related, just something that contrasts with what he wrote, which was this: "One thing that I was looking for during the install was Vehicle grounding and Electronics shielding. I did not want to turn on the radios and all I hear was a constant harmonic computer generated buzz. I was quite impressed with both the level of shielding and grounding used in this car..."

I guess I have the opposite POV, since I had to go out and buy a Radio Shack Ground Isolator and install it in the console, just to hook up an XM Sat radio unit to the Aux port. Then, low and behold, a few weeks later, I find out about the TSB from Toyota for this same issue.

My point, albeit subtle for some, is that the shielding IS NOT that great everywhere in the car, if you have to install a GROUND FAULT ISOLATOR on the AUX port of the audio system. What other Oopses are there in this car when it comes to shielding?

The NHTSA seems to think it's a valid issue at the least. See Update just posted.

 

I took it as an insult, just like your current retort. It seems there is always someone ready to provide loads of criticism without any suggestions or original thoughts of their own. There's one in every crowd - looks like you're it.

Apparently, you didn't read my initial posting well either, perhaps you were too busy simmering up your sarcastic retorts, as I pointed to SEVERAL possible causes, not just Bluetooth (although BT was first in the list).

My exact quote was: " Information Carrying Radio waves, Bluetooth and/or hands-free devices as a possible cause of UA in these recent Prius incidents. If my theory turns out to be correct, it would be easy to add shielding, using shielded cable or after-market installed toroidal coils, to reduce the hazard if it is caused by radio frequency interference."

It almost mirrors the latest info from the NHTSA Prius investigation posting, so I think it's spot on. If you have a better idea, I challenge you to post it. Your negativity so far has not been helpful, just hurtful.

 

Setting squabbling aside for a moment, let's look at some of the facts of this issue, as they exist at present:

1. The Prius, as well as several other Toyota vehicles, uses a "drive-by-wire" electronic throttle system that includes redundant sensors (like potentiometers) and circuits to feed the gas pedal position to its ECU. According to testimony on Capitol Hill, (and I do not recall the exact wording but hope to find it and post it here), this control circuit uses a very tiny amplitude signal, in the millivolts level to indicate pedal position.

My service rep states that the two sensors work exactly opposite of each other, one reading a higher signal when the pedal is fully depressed, while the other reads the opposite signal level. I cannot confirm this statement at this time.

2. Gen II Priuses are not supposed to be affected by the UIA problem at all, as all Toyota hybrids are supposed to have the brake override software routine installed already. This was told to me by my service rep last week, and similar verbage was stated in the Congressional hearings (...and I listened to all of them). So, stepping on the brake at any speed should override the tiny amplitude signal coming from the gas pedal and the ECU should "ignore" any gas pedal signal, and slow the vehicle.

THIS APPARENTLY DID NOT HAPPEN IN MR SIKE'S VEHICLE, in spite of all the jokes about his mishap including lack of knowledge about "the secret Neutral gear". His brake override software and system failed. (Like many others, we have tested ours and it works under normal conditions.)

3. Several other non-Priuses are more widely affected such as Lexus ES and Camry and some Tacomas. 52 people have been killed, mostly not in Priuses.

4. My theory is that there is an electronic signal interfering with the ECU that receives the gas pedal signal. I suspect Bluetooth or other information carrying radio waves, or it could be some kind of hands free device, or just plain old radio interference. It's just a theory, and one that would explain a randomly distributed occurrence that is hard to pin down.

6. NHTSA apparently knew about a yet-to-be publicized problem with the Prius back in Feb. 16, 2010, at least a week BEFORE the first Congressional hearings. Yet, there was almost nothing mentioned about this problem with the Prius in the Congressional hearings, and there is no recall of Priuses, other than the floormat. (correct me if I am wrong on this point). I do not recall if any Priuses had their gas pedals trimmed, tweaked or modified, as did other Toyota cars - mine warranted no recall whatsoever.

7. The Prius floormat hooks in place and is difficult to remove and is about the least likely suspect for this problem. In fact, with some of the incidents of UIA discussed on Capitol Hill, the floormats had already been removed from the vehicles in question.

8. The NHTSA website now has a statement on it that indicates that they suspect electromagnetic interference. It reads: "NHTSA IS SEEKING INFORMATION ABOUT... AND HOW TOYOTA ASSESSED POTENTIAL ELECTROMAGNETIC INTERFERENCE. THE AGENCY ALSO REQUIRES INFORMATION FROM TOYOTA ON WHY SOME MODELS OF VEHICLES WITH ELECTRONIC THROTTLE CONTROL WERE NOT INCLUDED IN THE RECALLS." This parallels my theory.

9. Some Priuses are known to have a minor ground fault if an external audio device (Ipod, sat radio, MP3 player) is attached to the Aux port of the audio system. Toyota has a fix for certain models, or you can install a Radio Shack Ground Fault Isolator like I did. Newer Prius may have this fix, or not. It may only affect the audio and nothing else.

10. A ground fault, grounding problem, or short circuit is another possible cause of this kind of problem. A professor from Southern Illinois University was able to duplicate a UIA situation in a toyota (not a prius) in 3 hours time with a makeshift box with pots and switches wired in parallel with the velocity pedal circuit. In these vehicles the brake override software may not have been present, or it may not have worked at all.

Those are the facts that I know about so far.

As Donald Rumsfeld would say, "there are known knowns, there are known unknowns, and there are unknown unknowns".

My effort is to try to narrow the field and find the cause, before someone else gets killed.

Please post your suggestions, or comments (please skip the criticisms - they aren't helpful).

 

Thanks, Don. I am new to this forum. It's a new idea to me. Everyone I asked said it was floormats... I am certainly not trying to be arrogant (that is your interpretation), and if it's been discussed before, that's great.

If you don't take my posting seriously, that's your choice. I came to my conclusions independently. Haven't posted here in years. And, from the kind of responses I keep getting that show a lack of courtesy, understanding, or even interest, and a high degree of techno-snobbish sarcasm, I don't know why anyone would want to post any idea on this site for some of you to trash.

It's easy to trash someone else's idea, folks. But, unless you have a better one, why would you want to do that.

 

So, as a closing post for the weekend, I challenge all those on this forum to post their best idea for the cause of this problem. Hold the sarcasm and snotty remarks - just your best idea. Provide as much detail as you can.

JAYMAN's posting for example, is excellent and helpful. I think I get the gist of what this digital oscope snapshot is showing, but even the best designed systems have their flaws. Like O-rings on the space shuttle, for example.