I don't agree. The first response would be to apply the brakes. The second response/realization would be that the car seems like it is fighting the brakes. The third would be to let up on the brakes to confirm suspicion #2. The forth would be to apply brakes again, as the cycle would start to repeat. Each time contributing to fade and all the while gaining speed at a fast rate, worsening that condition. Only the more capable of average drivers would think to slip it into neutral. Not the majority IMO. Plus, as has been mentioned, there are some theories that ponder if an electronic freeze or crash happened, that because auto trannys have so much electronic interaction with the engine and other asst bits, that possibly it might not have let the person put itin neutral even if and when they did get around to trying that. And the entire time they would be in traffic and dodging cars etc.
I am not defending that stance, just sayin'.
But my first responses above are probably what would happen, in order, for the masses.
There is also the issue of various mechanical lockouts in the way you put a shifter into neutral. In a panic situation, and in a car he was not familiar with, do you push in on the lever, pull on it? etc. With a bit of adrenaline he may have even forced it in such a way he broke it. We could speculate on this forever. I'll bet this thread has already gone full circle. Maybe on its third round now..
I'm not questioning why the Buffalo crash pilot didn't put the nose of the aircraft up or down, I'm just asking. Why on earth if its a given that the only cure for a stall is increased airspeed(prop planes included here) did this plane's pilot pull up on the nose of that plane?
That, as they say... is the $64,000 question. It is indeed possible he thought there was insufficient distance to descend. We will never know... only guess at why.
The only way to gain lift is to increase airspeed, and you don't increase airspeed by adding additional drag (increasing altitude) on the plane.
The first response would be to apply the brakes. The second response/realization would be that the car seems like it is fighting the brakes. The third would be to let up on the brakes to confirm suspicion #2. The forth would be to apply brakes again, as the cycle would start to repeat. Each time contributing to fade and all the while gaining speed at a fast rate, worsening that condition. Only the more capable of average drivers would think to slip it into neutral. Not the majority IMO.
Very plausible, ane possibly exactly what Saylors did. Again, not all "experts" will respond the same way. Ask "Sully" Sullenberger if he thinks all pilots would have successfully accomplished the landing he performed. He would tell you "no".
Yet, all the pilots would be professionally trained.
What is needed is analytically thinking, not just critical thinking.
There is no factual evidence either way but given Saylor's background and experience I think most of us would lean toward him having tried shifting into neutral.
Can't speak for anyone else, but my opinion is that if he had shifted into neutral, he'd be alive. You can shift into neutral with the CC full on and set to 150 mph and with the brakes burning. This is still a mechanical process, unless more epicycles are added to allow the mystery ghost that has disabled CC, brakes and ignition to also disable the transmission's shift lever.
We have been thru this before but I will try again. If he had the auto trans in the "shift" mode, he would have to push the shifter to the right and then up to neutral. If he just tried to push it straight up he would only change gears and it would be impossible to find neutral. If someone has the ability to post a link of a picture of the shift layout you will see what I mean.
I would think he tried to put it in neutral, but he was not thinking clearly, which is understandable under the circumstances. Plus, he was not familiar with the car.
No, the transaxle shifter control functionality has been "DBW" for many years now.
It was no time at all after the Saylor's crash that this Dr. Gilbert fellow demonstrated how (in a lab, not in the real world) logic faults could occur and not be caught by the recording mechanism.
Seems to me that anyone doing any investigation on this UA issue would attempt to duplicate or create a condition where the auto trans would not be able to shift into neutral, yet I haven't seen anyone even report on the issue.
From that, I'll assume that "those in the know" don't see that as a potenbtial problem, or possibly even a possibility.
Of course, anyone wishing to believe otherwise will still hang on to their belief.
Yeah, yeah, but the shift linkage itself is mechanical--activates a positioning switch. if it wasn't mechanical there would be no shift lever.
if you're saying he moved it but nothing happened, then that's another epicycle---the ghost would have to defeat the TCM as well as the ECM as well as the brakes, the CC and the ignition ...AND still keep the car running and driving.
Neat trick. Not bloody likely as they say in old British movies.
Yeah, yeah, but the shift linkage itself is mechanical--activates a positioning switch. if it wasn't mechanical there would be no shift lever.
if you're saying he moved it but nothing happened, then that's another epicycle---the ghost would have to defeat the TCM as well as the ECM as well as the brakes, the CC and the ignition ...AND still keep the car running and driving.
Neat trick. Not bloody likely as they say in old British movies.
To me, It seems that are a LOT of assumptions being made about how vehicles in general (and Toyotas specifically) are controlled.
WARNING: I am not an automotive engineer, and I may be totally incorrect here.
It is a given that the car’s ECM controls engine functions, but I have strong doubts that it also controls functions such as the automatic transmission shifter mechanism. In fact, I suspect the ECM only communicates with the transmission’s control functionaries (controllers), and couldn’t prevent one from shifting into neutral under any circumstances. While it could activate interlocks keeping one from shifting into "park", I know of no such interlock controlling "neutral".
I certainly wouldn’t give the ECM that capability, nor would I give it control over the brakes, windshield wipers, A/C system or radio. Simply put, it would make no sense.... if for no other reason than the one we are discussing here.
Its never good policy to put all of one’s eggs into a single basket.
Since the functionality of the engine and transaxle must be so tightly integrated, operated somewhat synchronously, in conjunction with each other, there is only one control module, typically a FAST microprocessor.
ABS, TC, BA, EBD, & VSC fucntions also require a high level of integration (VDIM) and so a single module is also used there.
Since the functionality of the engine and transaxle must be so tightly integrated, operated somewhat synchronously, in conjunction with each other, there is only one control module, typically a FAST microprocessor.
ABS, TC, BA, EBD, & VSC fucntions also require a high level of integration (VDIM) and so a single module is also used there.
I understand many autos combine the transmission and engine control modules, but you still haven’t answered the question at hand.
Can YOU demonstrate (and substantiate your claim) that the ECM would be able to prevent one from shifting into neutral, or possibly over-ride that action if done by the car’s driver?
While it is certainly a great theory to discuss, my question is whether or not it is actually possible. Other than in several forum discussions, I have yet to hear a single “qualified” individual state such a possibility exists in ANY vehicle.
At the end of the day, if you can’t show how a ECM caught in a closed-loop instruction cycle could actually cause that event to occur, then that idea is really no more substantial than one saying the car was cursed by a voodoo-practicing witch doctor.
If an ECM can over-ride the intent of the physical shifter mechanism, regardless of what gear/position is selected, then a car in park could suddenly jump into gear at any time.
That certainly doesn't sound like a scenario any automaker would allow to occur to me, simply for the liability issues. After all, there are interlocks requiring brake application before shifting out of park...
Besides, I could set the CC to run WOT (set it for top speed), and remove the brake light switch, so that the brake wouldn't shut off the CC, and rip out the ignition shut-off button, so that I can't shut off the engine----- and the car would still shift into neutral I betcha.
I suspect you are correct. I simply want to know if the whole "can't shift into neutral" scenario is actually possible or if its someone's wild (and possibly hopeful) imagination talking...
If no one knows, then simply say so, and make it clear its just a theory without any supporting evidence.
I have seen so many on these forums make statements that have no factual basis and then attempt to build upon those statements as if they were proven fact.
Well, it's not quite as simple as you make it out to be. The issue here is that there are actuators - essentially identical to the sensors in a typical pinball machine. Gear position X is Neutral, and if the sensor is tripped in that location, the computer tells the transmission to go to neutral.
But what happens if the computer stops registering inputs from the gear selector's sensors? Right - nothing happens. You move the thing around and it might as well be a non-responsive game controller at that point.
The issue is that if the main computer dies, everything attached to it also seizes up and only a physical override will do anything at all. Steering is still mechanical, so that works, and the emergency brake does as well, but that's it. Pulling the fuses is the only way to cut power at this point.
Oh - and easy way to test this theory is whether you can shift a Toyota in question into neutral with the engine off and the battery disconnected. I suspect nothing at all happens.
The issue is that if the main computer dies, everything attached to it also seizes up and only a physical override will do anything at all.
Agreed. The question remains...
Is there a physical or secondary over-ride occurring when shifting to neutral?
Of course, signals are sent to the ECM, but is there a secondary event occurring at the transmission level?
With the sheer number of ECM's replaced in a week's time in the USA, surely there would have been numerous complaints in the last few years if a bad ECM wouldn't allow the driver to shift to neutral or park.... Yet, I have never heard of this being an issue.
I can't accept the possibility that a cpu locked in a closed loop execution cycle will only allow for a wide-open throttle condition.
Here’s an example of what I’m discussing
I’m sitting in my den watching my TV. Unknown to me, my wife hides/steals/trashes the remote.
At this point, my TV is now in essence in a “run-away” condition, as I can’t remotely control it now. In an electronic-only world, I have lost my shifter.
But, I can hit the main power breaker (ie., turn off the key) and that will stop it.
And, there are additional circuit over-ride mechanisms I can use...none of which "crow-bar" the rest of the house circuitry...
I can hit the individual circuit breaker and stop it. I can pull the plug from the wall and stop it. I can hit the “power” button on the TV and stop it.
So, the real question is this
IS the shifter mechanism ONLY a remote control, or is it a combination remote and circuit over-ride device?
It wouldn’t necessarily need a physical connection. An actuator or solenoid on a separate circuit could easily perform this task, and I am sure there are other methods available.
If the computer dies, how does the car keep running? Or does it die "selectively"? I see more epicycles. It still sounds like a solution in search of facts.
Oh, I quite agree. The ECM controls more than just the throttle. Spark, timing, etc. For the engine to run wild with the ECM caught up in a closed loop is a bit far-fetched to me as well.
I'm just trying to take this "transmission can't shift into neutral" thing to its logical conclusion.
I don’t have any Toyota manuals, but I do have a service manual for a 2008 Nissan Altima with CVT auto transmission. So, I fully recognize Toyota may be completely different. I suspect they have a similar setup, however.
According to the manual, the transmission has a separate control module (TCM).
The engine speed signal is sent from the ECM to the TCM by CAN communication line.
From the manual
P0705 PARK/NEUTRAL POSITION SWITCH Description
• The PNP switch is included in the control valve assembly. • The PNP switch includes 4 transmission position switches. • TCM judges the selector lever position by the PNP switch signal.
So, in this automobile setup, even if the ECM controlling the engine went haywire, one could still shift into neutral successfully .
Unless both modules were corrupted in the perfect manner at the same time would it allow such an incident
I almost feel like you're kidding, pullin' my leg as it were.
Anyway...
Modern day automatic transmissions are strickly controlled electrically. They have up to 6 electric solenoids that are used by the engine/transaxle controlling ECU to select whatever function, gear ratio selection, lockup clutch, ATF line pressure, etc, for the condition that is currently optimal and is allowed by the shifter switch position.
The engine/transaxle ECU continuous reads, in a polling fashion, the shifter selection switches and coordinates the transaxle action, energization of those solenoids with the engine situation.
Lock the engine/transaxle ECU in a loop exclusively executing ONLY the CC "accel" instruction sequence, NO sensor polling, and all the car will be doing is trying to go faster and FASTER.
Toyota recalled 8 million cars to create a "smoke screen", "look over here, not over there. "
Like everyone else they had not a clue as to the actual SUA causative factor(s), and may not know even today. But to assuage public concern they had to shown some action.
Modern day automatic transmissions are strickly controlled electrically. They have up to 6 electric solenoids that are used by the engine/transaxle controlling ECU to select whatever function, gear ratio selection, lockup clutch, ATF line pressure, etc, for the condition that is currently optimal and is allowed by the shifter switch position
I believe my earlier postings clearly demonstrated you are the one in error, especially since there are separate control modules for the engine and transmission, at least in the Camry model.
But, feel free to believe whatever you wish, even if its incorrect.
Just for the record...
Another error of yours. From Post #1175 Sorry, you simply should not expect us to accept that as a true, well founded, statement, at least not once the car is also "at speed", 60 mph plus.
The FACTORY documentation for the '98 Camry at techinfo.toyota.com indicates a SINGLE Controller, ECM, for both the engine and transaxle. Shall I look at other years...?
"..Evidently, they had no problem doing it..."
Yes, I saw the video and admit that it confounds me. Why would Saylor and Smith have so much trouble...? The pictures of the rotors and pads on the Saylor vehicle show clearly that they were put to very severe use....
There is an indication that Saylor exceeded 100MPH, would that be the difference..?
This would require part of the ECM to fail and the rest of it to operate normally. It would have to selectively fail to defeat the brakes, transmission positioning switch, cruise control, and ignition off switch, but not the ignition itself, nor the transmission itself. This is like saying your laptop would defeat the OS but not the word processor.
The FACTORY documentation for the '98 Camry at techinfo.toyota.com indicates a SINGLE Controller, ECM, for both the engine and transaxle. Shall I look at other years...?
The pictures of the rotors and pads on the Saylor vehicle show clearly that they were put to very severe use....
There is an indication that Saylor exceeded 100MPH, would that be the difference..?
If it stops at 60 mph, I'm betting it would stop at 100 mph. Plus, why would anyone wait until they hit 100mph before attempting to brake?
However, its much more likely that he didn't apply full force. At the BMW performance center, in the ABS demonstration "test", its quite normal for drivers to resist braking at full force the first couple of attempts.
I was even guilty of such behavior my first time there.
As we discussed before it appears distinctly possible that this was the second SUA incident that Saylor had that day. Let's assume for the moment that that was the case.
So what worked to abate the problem the first time, and how much effort or time did Saylor use up trying the same thing...??
I seem to remember that he was parked on the right shoulder when the witness spotted him earler, that would mean that when he pulled back onto the roadbed he would have likely accelerated RAPIDLY, WOT, to the prevailing right lane speed.
~70 MPH before he lifted the gas pedal and discovered the engine was remaining WOT. How long does it take for that car to go from 70MPH to 100 or 100+ mph at WOT....?
Now, let's assume that this WAS the lexus, relatively NEW Lexus, that had an earlier SUA incident. How much brake use, SEVERE brake use, was made in the earlier incident..?
Isn't it true that SEVERE brake use before the NEW pads are well seated will often result in GLAZED pads with very little, reduced, frictional braking capability..?
Yes, this sounds as if I'm "grasping at straws", but if you think it through logically I think you might come to the same conclusion or theory.
My theory is that the computer didn't "die", it just got stuck executing a very tight sequence of instructions.
I have had my PC fail in a manner that the cursor could be moved about with the mouse but, seemingly, no other function worked. The only "escape" is a power cycle.
Many PC's go through that "phase", the cursor can be moved, only, during boot-up if you notice. It isn't that the computer has died, it's just that other instruction execution streams have higher priority at the moment.
As we discussed before it appears distinctly possible that this was the second SUA incident that Saylor had that day. Let's assume for the moment that that was the case.
So what worked to abate the problem the first time, and how much effort or time did Saylor use up trying the same thing...??
I seem to remember that he was parked on the right shoulder when the witness spotted him earler, that would mean that when he pulled back onto the roadbed he would have likely accelerated RAPIDLY, WOT, to the prevailing right lane speed.
~70 MPH before he lifted the gas pedal and discovered the engine was remaining WOT. How long does it take for that car to go from 70MPH to 100 or 100+ mph at WOT....?
Now, let's assume that this WAS the lexus, relatively NEW Lexus, that had an earlier SUA incident. How much brake use, SEVERE brake use, was made in the earlier incident..?
Isn't it true that SEVERE brake use before the NEW pads are well seated will often result in GLAZED pads with very little, reduced, frictional braking capability..?
Yes, this sounds as if I'm "grasping at straws", but if you think it through logically I think you might come to the same conclusion or theory.
No, I wouldn’t.
Even you admit that you are making several assumptions.
Frankly, without any substantiating backup evidence, your assumptions are no better than anyone else’s.
Brakes are pretty much “seated in” after 100 miles of stop and go traffic.
And, yes, I would personally say you are grasping at straws.
A phenomenal amount of things have to occur in an exact sequence for your theory to work, and even then, neither of us has the exposure to many of the design specifications to know whether or not your theory is even possible.
Sorry, but I would not come to the conclusions you have arrived at. As Mr. Shiftright has implied in an earlier posting, you seem to have developed your theory, and then attempted to make all the pieces fit.
"This would require part of the ECM to fail and the rest of it to operate normally.".
This is actually typical behavior. I often have things crash at the margin requiring a reboot, even kernel drivers, but except for that the system works.
We don't know the signal path, so you might be right or wrong.
Expressing it as a function,
shutoff = f( brake_status, x, y, z, ... )
1. We don't know when this function runs. It might even be piecemeal. There might be some condition that will prevent it from running.
2. We don't know how brake_status is determined - is it a hardware to an interrupt pin on the CPU? Or is it a CAN message from the ABS controller? Or something else?
3. We don't know the other factors in the equation. RPM? Gear?
4. We don't know how the boolean shutoff condition ends up actually shutting down the fuel. Does it zero the fuel calculation? Does it disable the injectors by disabling the firing hardware? Ignition?
The best case (which I seriously doubt) would the brake switch is on an interrupt line which initiates a high priority timer that upon expiration hits the hardware such that nothing else overrides the cutoff (until it detects brake release), and all this includes enough verification so a glitch (noise spike) on the brake line won't reset the timer, only a release.
Of course this would stall the engine which does not happen.
But here is a clue - the case of a false positive - fuel being cut off if there is no brake has not been reported to my knowledge. If the path was that short, robust, and reliable, errors would be toward this condition. If false positives are so rare, it is possible that false negatives are common.
So tell me, please, where and how the pieces DO NOT fit...
"...A phenomenal amount of things have to occur in an exact sequence..."
No, only ONE thing needs to occur, the task "flag" stored in memory to indicate the CC lever is in the "accel" mode doesn't get cleared as it should when the lever is released. The CC "accel" software routine then executes continuously, repetively, since each time it "tests", polls, the "flag" it remains "set".
You might even be able to partially simulate this effect by disconnecting the brake light switch circuit "branch" to the engine/transaxle ECU while holding the CC in "accel" mode.
Here’s a totally reasonable and acceptable alternate theory, just as plausible as any other, and it requires NO electronic mumbo-jumbo
Saylors is in a loaner car from the dealership. He is not as familiar with this car as he is his own vehicle. He is a reasonable driver and doesn’t want to abuse or trash a loaner vehicle. In other words, he’s a decent guy. He has his family with him, and he’s pre-occupied with family-related topics that any father would be pre-occupied with as well.
So, he gets behind the wheel, and has no knowledge of the earlier incident reported by a previous driver regarding pedal entrapment by the floor mat.
Off on his merry way, all is fine at first. However, once he gets on the freeway, the gas pedal is depressed far enough to get caught by the floor mat.
Now, he’s in a pickle. Can’t reach the pedal to pull it up, and doesn’t know how to turn the ignition off by holding the button for 3+ seconds. Panic sets in a bit, he doesn’t think about shifting into neutral, so he stomps down on the gas pedal several times in an attempt to get it to return to idle position.
This time, he gets lucky. The pedal releases from the entrapping mat, and now shaken, he pulls over the roadside to collect himself. He has no idea what happened, but being a new (and hi-line)car, he thinks surely it must have been a fluke thing.
After a few moments he’s back on the road. For some distance, all seems well once more. Again, the gas pedal gets entrapped, but this time, no luck in getting the pedal to release.
Panic hits again, so he really starts laying on the brakes , just not applying all his force. Remember, its not his car, and he wants to take care of it (and cause no damage that he has to pay for himself).
By the time he realizes he must apply more (maximum) braking pressure, he’s traveled far enough to have destroyed the brake linings, and now no amount of pressure applied is enough.
Well, isn't that the crux of the matter here, in that all of the "electronic-related-failure" theories being proposed here require a lot of assumptions?
We don't know the signal path, so you might be right or wrong.
Precisely my point. All of the theorizing going on here about UA is really not much more than gossip unless its based upon the actual system design specifications of the vehicles in question (Toyotas).
Yes, an assumption or educated guess, based on 40+ years, continuing this very day, of over-seeing development of real-time process control code, programming.
But if it were me, I would not use a flag to indicate that the accell button of the CC had been depressed, for just the reasons you mentioned.
Use a flag, if you like, to tell the system the the CC has been turned on. Then periodically (every 10 msec), poll the input that represents the state of the accel button. If the accel button is depressed, then call a function, one time, that increases the set point point of the CC controlled throttle positioner by a small amount, say something that would increase the speed of the vehicle by 0.1 mph. This should be a very simple, small function - a handful of lines of code whose correctness can be easily verified.
With this approach, there is no flag that can get stuck and cause the car to continue to accelerate.
Comments
I am not defending that stance, just sayin'.
But my first responses above are probably what would happen, in order, for the masses.
I'm talking about being in a car when the engine is racing out of control and the brakes are not stopping the car !!!
We could speculate on this forever. I'll bet this thread has already gone full circle. Maybe on its third round now..
What happened to the Saylors will NEVER EVER EVER happen to anyone who follows this forum.
We here all KNOW to put the car in neutral in that situation.
Whew !!!
That, as they say... is the $64,000 question. It is indeed possible he thought there was insufficient distance to descend. We will never know... only guess at why.
The only way to gain lift is to increase airspeed, and you don't increase airspeed by adding additional drag (increasing altitude) on the plane.
Very plausible, ane possibly exactly what Saylors did. Again, not all "experts" will respond the same way. Ask "Sully" Sullenberger if he thinks all pilots would have successfully accomplished the landing he performed. He would tell you "no".
Yet, all the pilots would be professionally trained.
What is needed is analytically thinking, not just critical thinking.
There is no factual evidence either way but given Saylor's background and experience I think most of us would lean toward him having tried shifting into neutral.
I would think he tried to put it in neutral, but he was not thinking clearly, which is understandable under the circumstances. Plus, he was not familiar with the car.
2013 LX 570 2016 LS 460
No, the transaxle shifter control functionality has been "DBW" for many years now.
Seems like you are lacking some understanding on the issue.
Toyota never said it was driver error. It said it had issues with floor mats and gas pedals catching on those mats.
That was the reason(s) for the recalls.
Driver error comes in when the driver doesn't understand how to recover from the condition caused by the mats' issue.
Those who wish to make this an "electronic-related" issue don't seem to be able to grasp that concept.
It was no time at all after the Saylor's crash that this Dr. Gilbert fellow demonstrated how (in a lab, not in the real world) logic faults could occur and not be caught by the recording mechanism.
Seems to me that anyone doing any investigation on this UA issue would attempt to duplicate or create a condition where the auto trans would not be able to shift into neutral, yet I haven't seen anyone even report on the issue.
From that, I'll assume that "those in the know" don't see that as a potenbtial problem, or possibly even a possibility.
Of course, anyone wishing to believe otherwise will still hang on to their belief.
Can YOU create and duplicate such a condition?
if you're saying he moved it but nothing happened, then that's another epicycle---the ghost would have to defeat the TCM as well as the ECM as well as the brakes, the CC and the ignition ...AND still keep the car running and driving.
Neat trick. Not bloody likely as they say in old British movies.
if you're saying he moved it but nothing happened, then that's another epicycle---the ghost would have to defeat the TCM as well as the ECM as well as the brakes, the CC and the ignition ...AND still keep the car running and driving.
Neat trick. Not bloody likely as they say in old British movies.
To me, It seems that are a LOT of assumptions being made about how vehicles in general (and Toyotas specifically) are controlled.
WARNING: I am not an automotive engineer, and I may be totally incorrect here.
It is a given that the car’s ECM controls engine functions, but I have strong doubts that it also controls functions such as the automatic transmission shifter mechanism. In fact, I suspect the ECM only communicates with the transmission’s control functionaries (controllers), and couldn’t prevent one from shifting into neutral under any circumstances. While it could activate interlocks keeping one from shifting into "park", I know of no such interlock controlling "neutral".
I certainly wouldn’t give the ECM that capability, nor would I give it control over the brakes, windshield wipers, A/C system or radio. Simply put, it would make no sense.... if for no other reason than the one we are discussing here.
Its never good policy to put all of one’s eggs into a single basket.
ABS, TC, BA, EBD, & VSC fucntions also require a high level of integration (VDIM) and so a single module is also used there.
ABS, TC, BA, EBD, & VSC fucntions also require a high level of integration (VDIM) and so a single module is also used there.
I understand many autos combine the transmission and engine control modules, but you still haven’t answered the question at hand.
Can YOU demonstrate (and substantiate your claim) that the ECM would be able to prevent one from shifting into neutral, or possibly over-ride that action if done by the car’s driver?
While it is certainly a great theory to discuss, my question is whether or not it is actually possible. Other than in several forum discussions, I have yet to hear a single “qualified” individual state such a possibility exists in ANY vehicle.
At the end of the day, if you can’t show how a ECM caught in a closed-loop instruction cycle could actually cause that event to occur, then that idea is really no more substantial than one saying the car was cursed by a voodoo-practicing witch doctor.
If an ECM can over-ride the intent of the physical shifter mechanism, regardless of what gear/position is selected, then a car in park could suddenly jump into gear at any time.
That certainly doesn't sound like a scenario any automaker would allow to occur to me, simply for the liability issues. After all, there are interlocks requiring brake application before shifting out of park...
If no one knows, then simply say so, and make it clear its just a theory without any supporting evidence.
I have seen so many on these forums make statements that have no factual basis and then attempt to build upon those statements as if they were proven fact.
LOL!!!!
But what happens if the computer stops registering inputs from the gear selector's sensors? Right - nothing happens. You move the thing around and it might as well be a non-responsive game controller at that point.
The issue is that if the main computer dies, everything attached to it also seizes up and only a physical override will do anything at all. Steering is still mechanical, so that works, and the emergency brake does as well, but that's it. Pulling the fuses is the only way to cut power at this point.
Oh - and easy way to test this theory is whether you can shift a Toyota in question into neutral with the engine off and the battery disconnected. I suspect nothing at all happens.
Agreed. The question remains...
Is there a physical or secondary over-ride occurring when shifting to neutral?
Of course, signals are sent to the ECM, but is there a secondary event occurring at the transmission level?
With the sheer number of ECM's replaced in a week's time in the USA, surely there would have been numerous complaints in the last few years if a bad ECM wouldn't allow the driver to shift to neutral or park.... Yet, I have never heard of this being an issue.
I can't accept the possibility that a cpu locked in a closed loop execution cycle will only allow for a wide-open throttle condition.
Here’s an example of what I’m discussing
I’m sitting in my den watching my TV. Unknown to me, my wife hides/steals/trashes the remote.
At this point, my TV is now in essence in a “run-away” condition, as I can’t remotely control it now. In an electronic-only world, I have lost my shifter.
But, I can hit the main power breaker (ie., turn off the key) and that will stop it.
And, there are additional circuit over-ride mechanisms I can use...none of which "crow-bar" the rest of the house circuitry...
I can hit the individual circuit breaker and stop it.
I can pull the plug from the wall and stop it.
I can hit the “power” button on the TV and stop it.
So, the real question is this
IS the shifter mechanism ONLY a remote control, or is it a combination remote and circuit over-ride device?
It wouldn’t necessarily need a physical connection. An actuator or solenoid on a separate circuit could easily perform this task, and I am sure there are other methods available.
I'm just trying to take this "transmission can't shift into neutral" thing to its logical conclusion.
According to the manual, the transmission has a separate control module (TCM).
The engine speed signal is sent from the ECM to the TCM by CAN communication line.
From the manual
P0705 PARK/NEUTRAL POSITION SWITCH
Description
• The PNP switch is included in the control valve assembly.
• The PNP switch includes 4 transmission position switches.
• TCM judges the selector lever position by the PNP switch signal.
So, in this automobile setup, even if the ECM controlling the engine went haywire, one could still shift into neutral successfully .
Unless both modules were corrupted in the perfect manner at the same time would it allow such an incident
What are the odds?
http://www.dealerdirectparts.com/2010-TOYOTA-CAMRY-XLE-Auto-Trans-Control-U-p/to- yota-6027405-camry-xle-4.htm
Anyway...
Modern day automatic transmissions are strickly controlled electrically. They have up to 6 electric solenoids that are used by the engine/transaxle controlling ECU to select whatever function, gear ratio selection, lockup clutch, ATF line pressure, etc, for the condition that is currently optimal and is allowed by the shifter switch position.
The engine/transaxle ECU continuous reads, in a polling fashion, the shifter selection switches and coordinates the transaxle action, energization of those solenoids with the engine situation.
Lock the engine/transaxle ECU in a loop exclusively executing ONLY the CC "accel" instruction sequence, NO sensor polling, and all the car will be doing is trying to go faster and FASTER.
Like everyone else they had not a clue as to the actual SUA causative factor(s), and may not know even today. But to assuage public concern they had to shown some action.
Modern day automatic transmissions are strickly controlled electrically. They have up to 6 electric solenoids that are used by the engine/transaxle controlling ECU to select whatever function, gear ratio selection, lockup clutch, ATF line pressure, etc, for the condition that is currently optimal and is allowed by the shifter switch position
I believe my earlier postings clearly demonstrated you are the one in error, especially since there are separate control modules for the engine and transmission, at least in the Camry model.
But, feel free to believe whatever you wish, even if its incorrect.
Just for the record...
Another error of yours. From Post #1175
Sorry, you simply should not expect us to accept that as a true, well founded, statement, at least not once the car is also "at speed", 60 mph plus.
Watch the video
http://www.insideline.com/car-video/fe_48.html
Evidently, they had no problem doing it.
You're reaching a bit too far to support your position, IMO. Especially since you offer no supporting materials.
"..Evidently, they had no problem doing it..."
Yes, I saw the video and admit that it confounds me. Why would Saylor and Smith have so much trouble...? The pictures of the rotors and pads on the Saylor vehicle show clearly that they were put to very severe use....
There is an indication that Saylor exceeded 100MPH, would that be the difference..?
Actually, yes I would
Specifically, for the 2010 Camry XLE.
I based my comments off of the info from the link below
http://www.dealerdirectparts.com/2010-TOYOTA-CAMRY-XLE-Auto-Trans-Control-U-p/to- yota-6027405-camry-xle-4.htm
Possibly a change?
I understand your info was based on a 2008 model.
There is an indication that Saylor exceeded 100MPH, would that be the difference..?
If it stops at 60 mph, I'm betting it would stop at 100 mph. Plus, why would anyone wait until they hit 100mph before attempting to brake?
However, its much more likely that he didn't apply full force. At the BMW performance center, in the ABS demonstration "test", its quite normal for drivers to resist braking at full force the first couple of attempts.
I was even guilty of such behavior my first time there.
http://www.trademotion.com/partlocator/index.cfm?action=getJointLocator&siteid=2- 14915&chapter=§ionids=3,2413&groupid=10046&subgroupid=60471&make=34&model=Ca- mry&year=2010&catalogid=1&displayCatalogid=0
As we discussed before it appears distinctly possible that this was the second SUA incident that Saylor had that day. Let's assume for the moment that that was the case.
So what worked to abate the problem the first time, and how much effort or time did Saylor use up trying the same thing...??
I seem to remember that he was parked on the right shoulder when the witness spotted him earler, that would mean that when he pulled back onto the roadbed he would have likely accelerated RAPIDLY, WOT, to the prevailing right lane speed.
~70 MPH before he lifted the gas pedal and discovered the engine was remaining WOT. How long does it take for that car to go from 70MPH to 100 or 100+ mph at WOT....?
Now, let's assume that this WAS the lexus, relatively NEW Lexus, that had an earlier SUA incident. How much brake use, SEVERE brake use, was made in the earlier incident..?
Isn't it true that SEVERE brake use before the NEW pads are well seated will often result in GLAZED pads with very little, reduced, frictional braking capability..?
Yes, this sounds as if I'm "grasping at straws", but if you think it through logically I think you might come to the same conclusion or theory.
I have had my PC fail in a manner that the cursor could be moved about with the mouse but, seemingly, no other function worked. The only "escape" is a power cycle.
Many PC's go through that "phase", the cursor can be moved, only, during boot-up if you notice. It isn't that the computer has died, it's just that other instruction execution streams have higher priority at the moment.
http://computer.yourdictionary.com/livelock
So what worked to abate the problem the first time, and how much effort or time did Saylor use up trying the same thing...??
I seem to remember that he was parked on the right shoulder when the witness spotted him earler, that would mean that when he pulled back onto the roadbed he would have likely accelerated RAPIDLY, WOT, to the prevailing right lane speed.
~70 MPH before he lifted the gas pedal and discovered the engine was remaining WOT. How long does it take for that car to go from 70MPH to 100 or 100+ mph at WOT....?
Now, let's assume that this WAS the lexus, relatively NEW Lexus, that had an earlier SUA incident. How much brake use, SEVERE brake use, was made in the earlier incident..?
Isn't it true that SEVERE brake use before the NEW pads are well seated will often result in GLAZED pads with very little, reduced, frictional braking capability..?
Yes, this sounds as if I'm "grasping at straws", but if you think it through logically I think you might come to the same conclusion or theory.
No, I wouldn’t.
Even you admit that you are making several assumptions.
Frankly, without any substantiating backup evidence, your assumptions are no better than anyone else’s.
Brakes are pretty much “seated in” after 100 miles of stop and go traffic.
And, yes, I would personally say you are grasping at straws.
A phenomenal amount of things have to occur in an exact sequence for your theory to work, and even then, neither of us has the exposure to many of the design specifications to know whether or not your theory is even possible.
Sorry, but I would not come to the conclusions you have arrived at. As Mr. Shiftright has implied in an earlier posting, you seem to have developed your theory, and then attempted to make all the pieces fit.
This is actually typical behavior. I often have things crash at the margin requiring a reboot, even kernel drivers, but except for that the system works.
We don't know the signal path, so you might be right or wrong.
Expressing it as a function,
shutoff = f( brake_status, x, y, z, ... )
1. We don't know when this function runs. It might even be piecemeal. There might be some condition that will prevent it from running.
2. We don't know how brake_status is determined - is it a hardware to an interrupt pin on the CPU? Or is it a CAN message from the ABS controller? Or something else?
3. We don't know the other factors in the equation. RPM? Gear?
4. We don't know how the boolean shutoff condition ends up actually shutting down the fuel. Does it zero the fuel calculation? Does it disable the injectors by disabling the firing hardware? Ignition?
The best case (which I seriously doubt) would the brake switch is on an interrupt line which initiates a high priority timer that upon expiration hits the hardware such that nothing else overrides the cutoff (until it detects brake release), and all this includes enough verification so a glitch (noise spike) on the brake line won't reset the timer, only a release.
Of course this would stall the engine which does not happen.
But here is a clue - the case of a false positive - fuel being cut off if there is no brake has not been reported to my knowledge. If the path was that short, robust, and reliable, errors would be toward this condition. If false positives are so rare, it is possible that false negatives are common.
"...A phenomenal amount of things have to occur in an exact sequence..."
No, only ONE thing needs to occur, the task "flag" stored in memory to indicate the CC lever is in the "accel" mode doesn't get cleared as it should when the lever is released. The CC "accel" software routine then executes continuously, repetively, since each time it "tests", polls, the "flag" it remains "set".
You might even be able to partially simulate this effect by disconnecting the brake light switch circuit "branch" to the engine/transaxle ECU while holding the CC in "accel" mode.
Saylors is in a loaner car from the dealership. He is not as familiar with this car as he is his own vehicle. He is a reasonable driver and doesn’t want to abuse or trash a loaner vehicle. In other words, he’s a decent guy. He has his family with him, and he’s pre-occupied with family-related topics that any father would be pre-occupied with as well.
So, he gets behind the wheel, and has no knowledge of the earlier incident reported by a previous driver regarding pedal entrapment by the floor mat.
Off on his merry way, all is fine at first. However, once he gets on the freeway, the gas pedal is depressed far enough to get caught by the floor mat.
Now, he’s in a pickle. Can’t reach the pedal to pull it up, and doesn’t know how to turn the ignition off by holding the button for 3+ seconds. Panic sets in a bit, he doesn’t think about shifting into neutral, so he stomps down on the gas pedal several times in an attempt to get it to return to idle position.
This time, he gets lucky. The pedal releases from the entrapping mat, and now shaken, he pulls over the roadside to collect himself. He has no idea what happened, but being a new (and hi-line)car, he thinks surely it must have been a fluke thing.
After a few moments he’s back on the road. For some distance, all seems well once more. Again, the gas pedal gets entrapped, but this time, no luck in getting the pedal to release.
Panic hits again, so he really starts laying on the brakes , just not applying all his force. Remember, its not his car, and he wants to take care of it (and cause no damage that he has to pay for himself).
By the time he realizes he must apply more (maximum) braking pressure, he’s traveled far enough to have destroyed the brake linings, and now no amount of pressure applied is enough.
Seconds later, he crashes.
Isn't that an assumption on your part - that a "task flag" is used to indicate that the accel button is depressed?
Precisely my point. All of the theorizing going on here about UA is really not much more than gossip unless its based upon the actual system design specifications of the vehicles in question (Toyotas).
Use a flag, if you like, to tell the system the the CC has been turned on. Then periodically (every 10 msec), poll the input that represents the state of the accel button. If the accel button is depressed, then call a function, one time, that increases the set point point of the CC controlled throttle positioner by a small amount, say something that would increase the speed of the vehicle by 0.1 mph. This should be a very simple, small function - a handful of lines of code whose correctness can be easily verified.
With this approach, there is no flag that can get stuck and cause the car to continue to accelerate.