Archive for the ‘Runaway Toyotas’ Category

Probe into Toyota throttle control intensifies, and now Chevy Cobalt electric power steering under scrutiny. Is new technology getting ahead of safety?

Thursday, February 4th, 2010

Are we letting new electronic car control systems outpace development of  fail safe mechanisms at times of failure?

Electronic devices and systems, have, and always will be prone to both unpredictable intermittent and sudden total failure.

When electronic controls and systems are used to control vital systems in cars, such as speed, steering, braking and shifting, there is grave cause for concern.  Added to which an automobile is a harsh environment for electronics.

Toyota’s recent problems with unwanted acceleration have brought these issues into focus. Worries are intensified by the fact that Toyota almost certainly has no clue as to the real cause of these incidents, but have come up with a couple of face saving sham solutions.  More likely than not this will result in larger helpings of egg on the old visage, giving new meaning to “loss of face.”

Today I had my Toyota Camry hybrid out to the dealer to get numbers off the radio/CD/GPS unit which has developed problems.  I understand from the service department this is not infrequent.  They checked the accelerator pedal and confirmed it as a Denso and not CTS.  They checked the recent recall data and said there is a carpet recall.  I told them that the carpet is firmly fixed by stout hooks, and the pedal hung from above, and nowhere near the carpet!  The service tech agreed.  With a twinkle in his eye said, “But we will be doing something to the carpet.”  Now the word so often used by  Click and Clack fits the situation perfectly: – “BOGUS!”  It is also a total waste of everyone’s time.

Toyota’s situation is rapidly deteriorating to farce.

However the issues remain serious.  This report leaves open to question whether under some circumstances the driver can exert any control over a Toyota vehicle at all.

This report gives credence to the belief that the accelerator pedal fix is a smoke screen.

Despite Ray LaHood’s retraction the Houston Police Department have parked their Toyota Camry Hybrids, and they are not involved in the pedal recall!

Toyota now have company with accidents caused by electronic controls in vital places of GM vehicles.  The electronic power steering in the Chevy Cobalt is now under intensive government scrutiny, after failure reports, accidents and deaths.  GM have this system on all their vehicles with engines 2.4 liters or less.  Ford say they will have the system on 80 to 90% of their vehicles by 2012.

From Wikipedia, this is the rational for moving to electric steering: -

[The aim of steer-by-wire technology is to completely do away with as many mechanical components (steering shaft, column, gear reduction mechanism, etc.) as possible. Completely replacing conventional steering system with steer-by-wire holds several advantages, such as:

  • The absence of steering column simplifies the car interior design.
  • The absence of steering shaft, column and gear reduction mechanism allows much better space utilization in the engine compartment.
  • The steering mechanism can be designed and installed as a modular unit.
  • Without mechanical connection between the steering wheel and the road wheel, it is less likely that the impact of a frontal crash will force the steering wheel to intrude into the driver's survival space.
  • Steering system characteristics can easily and infinitely be adjusted to optimize the steering response and feel.

As of 2007 there are no production cars available that rely solely on steer-by-wire technology due to safety, reliability and economic concerns, but this technology has been demonstrated in numerous concept cars and the similar fly-by-wire technology is in use in both military and civilian aviation applications. Removing the mechanical steering linkage in road going vehicles would require new legislation in most countries.]

In pursuit of government mandates to stretch the gallon of gas ever further, manufacturers are forced into these complex high tech systems.  In order to keep prices down the temptation to compromise safety grows by the mandate.

So if this is the way of the future, the same rigorous testing review and oversight will have to be given to automobiles as aircraft.

In addition, it is instructive to note that in the errant Toyota vehicles no OBD fault codes have shown up, and the problem goes away at least for a period of time after re starting.  To me this indicates that like aircraft, automobiles will have to have black boxes, that record data form every sensor, every driver command and computer command.  If this technology was in Toyota vehicles now, I very much doubt any facts about these serious incidents would now be in doubt.  We would then be well on our way to the right fix.

The problem is that the cost of all this is likely to put the cost of vehicle ownership outside the reach of most.  Cost I suspect will not only be prohibitive in terms of cost but maintenance.  The cost of maintaining older high mileage vehicles will put them out of the reach of low income families.  The personal and family car is destined to become a luxury for the few.

This incredible news just in today.  Our government could not get people drunk in a brewery.  Our government seems bought and paid for through out and that’s sad.

A fix for Toyota’s problem. A hypothesis that explains the facts: a way towards solutions.

Friday, January 29th, 2010

Toyota claim that it is a sticky accelerator mechanism that is causing unwanted and unexpected acceleration in their cars.  I think this is unlikely and here is why.

I have watched all the witness accounts of this problem in Toyota vehicles on the ABC News site.  Now one of these vehicles spontaneously accelerated while going down hill with the driver’s foot off the accelerator pedal.  So a sticky accelerator does not explain what this driver experienced.

Now it is valid to ask if a retired critical care physician like myself has any business posting about a problem like this.  I would plead that physicians are trained and should posses critical analysis  skills, and quickly be able to put a hypothesis together that explains all the facts.

In addition I have worked on cars and engines since my preteen years.  I work on antique and modern engines, and I’m familiar with the components of engine controls.  In addition I have had an over riding interest in electronics, and have put big systems together and I’m familiar with some aspects of circuit design and do my own service work.

In addition my son Andrew is an electrical engineer who graduated summa cum laude from the University of Minnesota.  He has reviewed this hypothesis and finds it more plausible than statements from Toyota.  We also have a vested interest.  He owns a Toyota Camry and a RAV 4.  I own a Toyota Camry.

I have managed to find a copy of the  Toyota throttle circuit in block diagram at least

As you can see it is a servo type of motor with Hall effect control.

Now I came upon this post where a mechanic on eHow says the opening of the PVC valve opens at a bad place on Toyota engines and sticks up the throttle body.

Now if the PCV valve is putting oil deposits in the area of the Hall sensor, this could easily cause the Hall effect device to send erroneous information the the ECM and explain why this problem is so prevalent in so many Toyota models.

Now if that is the problem there are two potential steps Toyota could take to remedy the problem.  When the break light is activated, a voltage should be taken off that to a relay or preferably a MOS FET switch to interrupt the signal from pins 66 and 80 of the PCM to pins 3 and 5 on the throttle body.  Now if the PCV valve effluent is gumming up the throttle body, then the throttle body should be redesigned to have the PCV valve breath into the intake manifold like on every other engine I know of.  The reason for the latter is that if the mechanism is gummed up in the throttle body then breaking power to the throttle body servo motor would not work.

The only fly in the ointment I see here is that the throttle body air flow control looks rather nasty and over complicated from the photographs.  Instead of the usual brass butterfly rotating against spring closure, this Toyota design appears to have a geared louver type of control, and cheap plastic gears at that.  I have a suspicion it might not close with power interrupted to the throttle body servo motor, like the usual arrangement would.  If that is the case, then Toyota would have to totally redesign the throttle body to make a break override be fail safe and operate independently of ECM failure.

The problem has now been documented to occur over a nine year period and seems to involve 2005 models preferentially for some reason.  So the cost to Toyota could be enormous.  If the throttle does not close at zero voltage to the throttle body motor, then this would require a new throttle body design, a new ECM module, and modification and or replacement of the throttle body motor.  This would likely cost more than older and or high mileage vehicles are worth.

If the throttle closes at zero voltage to the servo motor then the fix could be relatively simple.

Questions journalist should be asking Toyota.

1).  How will changing the throttle mechanism prevent random acceleration going down hill when the accelerator was not depressed?

2).  Does the throttle close with no power applied to the throttle servo motor?

3).  Will you quickly provide all throttle control parts, circuit details and software for immediate peer review?  If not why not?

This is I think a very dangerous situation.  I think it is valid question to ash whether or not Toyotas should be grounded until this problem is solved.

Now my hypothesis is very unlikely to be correct in every detail, but I would bet the cause and solution is something along these lines.

Runaway Toyotas: The Real Issues Behind the Scandal.

Wednesday, January 27th, 2010

In modern engine management the accelerator no longer has a mechanical connection to the throttle butterfly, or injector pump slide in diesels. The reason is fuel economy.

In a standard mechanical control, the accelerator sets the air flow and fuel flow follows. With the accelerator sending a signal to the engine management control via a sending unit, the engine management is in control of fuel and air independently.

This system came to Europe first in the nineties. They had runaway cars and especially heavy goods vehicles and IEC 61508 standard came about. The testing and compliance are rigorous and the engine has to die if a problem is detected with the system and the vehicle can not be restarted.

Now in 2004 Toyota withdrew models from Europe, the Camry being first. They claimed it was due to poor sales, but on my frequent visits I saw lots of them. I’m now convinced Toyota removed the vehicles from Europe because they could not meet IEC 61508.

The dealers have been urging Toyota to bring back the Camry but they have refused.

Ford are going through this process in Europe now and this is what is involved.

I think the press have done a sloppy job on this story so far.  I now find that this issue has been suppressed since 2001!

As a Toyota Camry owner, I think Toyota have a huge problem. I think Toyota and other manufacturers should be made to show their systems can meet IEC 61508. I personally don’t think another Toyota involved in this should move off the lot until they can!

This just posted.

This is how Toyota treat their engineers.