Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Toyota/Lexus transaxle shift delay



  • user777user777 Posts: 3,341
    getting on the gas when making a turn, similar to the scenario where you slow down in the turning lane to a relatively slow speed, waiting for an opening in traffic to go HARD left into a shopping center...

    i mean, did someone test the theory we may have the engine derating because of yaw-rate detection of VSC.
  • wwestwwest Posts: 10,706
    I'm pretty sure I have seen several posts, not necessarily here at Edmunds, about drivers experiencing the extended delay while turning. Obviously the entry to the turn might have invoved a standard TSB circumstance.
  • scoti1scoti1 Posts: 676
    The delay while turning has been reported here at Edmunds, too. I recall posters stating they see an opening in traffic, pull into the intersection expecting the car to accelerate only to have it delay with on-coming traffic approaching. But I have also read of the same delay in other situations not involving a turn, such as merging into traffic, trying to speed up to pass a vehicle, etc.
  • wwestwwest Posts: 10,706
    The service manager at Lexus of Bellevue told me that the really simply way to disable VSC temporarily was to create an engine fault.

    So I disconnected the MAF/IAT sensor connector on my 2001 AWD RX300 while the engine was running. The engine died almost immediately and wouldn't restart. When I reconnected the MAF/IAT it started right back up but with an engine & VSC failure indication.

    After about 4 drive cycles the indications went out.

    So for any of you that are experiencing the extended delay/hesitation symptom if you want to try and see if VSC is somehow related.....
  • user777user777 Posts: 3,341
    I'm still hoping that someone with a significant problem would take their vehicle to the dealer and presuming it's been looked at before, politely ask that the throttle body be swapped out.

    WWEST, the position sensor is essentially a rotary potentiometer. It could have non-linear characteristics at the low end. Just as important, there is a IDL (Idle Switch) which senses Throttle at/near zero. Your shop manuals must show this and the range of Throttle degrees where it is still sensed "closed". It's possible in my mind it is malfunctioning and sensing closed for an entirely too large range of throttle opening.

    It is NOT a "Hall effect" device but rather quite mechanical and low-tech.

    go to

    and click on technical articles. Look at page 3 onward of article 16.

    BTW - lots of good information on that site!
  • user777user777 Posts: 3,341
    interesting... it's intuitively obvious i suppost that faulting the Mass AirFlow sensor would fault the stability control function...

    THAT's one of the things I'm writing about when I suggest we step back and consider Human Factors and Complex Systems. I mean, who had a mental model accurate to have believed cause / effect for this one?

    No lying now.
  • hylynerhylyner Posts: 216
    Glad to see the discussion back on track.
    FYI,I found the following passage while browsing through the old (now closed) 'Engine Hesitation' discussion.
    There are other options to modify throttle response by mechanical means with DBW systems.
    Here's one way---a quote from a Denso technical publication re accelerator pedal modules in DBW systems:
    "The electric output characteristics of the sensor can be set in accordance with customer’s specifications.
    DENSO provides two types of accelerator pedal modules – resin rod type and iron rod type – to meet customer’s needs."

    For those who question reliablity of DBW systems, because they use less mechanical components, they are considered less susceptible to wear, and generally require less maintenance than conventional systems.
    They are more reliable--but they don't behave like conventional systems.
    Perhaps those who question reliability are confusing reliability with expectations in performance.
    Make no mistake, currently about 60 percent of today's vehicles are equipped with DBW systems.
    Within two to three years this technology will be adopted across the board.
    What we're seeing today are mainly second generation designs.
    Response parameters still need work in just about all systems available today--and for all makes using 2nd generation technology.
    Toyota isn't the only carmaker with this issue.
    No question, there is still much room for improvement in these systems re throttle response under changing conditions.
    We can expect a third generation improvement in response characteristics to be included many 2006 models, and by 2007,there should be improved systems available throughout the industry.
  • hylynerhylyner Posts: 216
    Attempting to form valid statistics from people who post on Edmunds forums is a challenge !

    You sure got that right Bettersafe.
    You've shown good reason not to attach validity to at least some (who knows the right number) posted stories about this issue. Information from impeccable sources isn't always impeccable!!
    However, in line with what I've advocated many times re objectivity in "Identifying The Problem", It certainly wouldn't hurt to try an get something in the way of useful data from them--where possible.
    Would it make any sense for you folks who profess to be immersed in the issue to develop a check list of appropriate questions for those who do post about problems they're having?
    You could then ask for feedback re those specific questions. (Examples--How is the vehicle used; What are specific hesitation characteristics; Under what/when/where specific conditions does it occur; Principal driver; Vehicle mileage; What options/equipment on the vehicle.......and so on)
    In doing so, over time you might develop consistent "profiles/patterns" which would certainly help focus on possible causes--thus minimize a lot of guesswork which seems to be prevailent in your discussions.
    If you're sincere about finding answers , and not just having fun--as you said "We enjoy daily banter on the topic", this approach might be worth considering.
    If you agree, a good start might be to get feedback from all of us re what might be good questions to ask.
  • billranbillran Posts: 113
    Would it make any sense for you folks who profess to be immersed in the issue to develop a check list of appropriate questions for those who do post about problems they're having?

    Thats a good idea hylyner. The only problem with it is that at the current time, there is not a single actual owner posting that they have a problem. Even at the height of activity there were never more than 3 or 4 regular posters who said they were experiencing hesitation, and then a few others who came and went. And, several of those who had the TSB applied, reported that solved the problem.
  • Count me as a someone who has a problem. My dad has a highlander 2004, v6, with a terrible hesitation problem. It bothers him, but he's not the type to complain too much, certainly not bring it to the govt. He's complained to the dealer and they said, "that's the way it is supposed to be." So he lives with it. He's a very cautious and (older) driver so I don't think he cares that much...
  • billranbillran Posts: 113
    Has he had the TSB applied? That has been reported as very successful by several people. In any case that is a good place to start.
  • hylynerhylyner Posts: 216
    Thanks for the quick feedback.
    It would be helpful for the purposes of this forum if you could provide more detailled information, for example,along the lines of the items I listed above.
    Specifics such as mileage on the vehicle; was it purchased new; did the hesitation start right away or after some miles were run up; does the hesitation come and go; is it more prevailent some of the time; have you driven the vehicle; describe the characteristics of hesitation--upshift, downshift,length of hesitation interval; does it do it with WOT or partial throttle; does it do it when turning; type or style of driving; have any attempts been made to fix it--if so what was done; can you make it disappear by using the throttle in another way........and so on.
    Answers to any or all of these questions would be helpful, and any other info you (or someone else) might think of would be appreciated.
    Hope you can find some time to respond. Thanks in advance.
  • No, he hasn't. The local dealer didn't say there was one. I'll tell him to bring it in and ask. The darn thing drives me nuts when I drive it (that's why I'm here, obviously :) ) The car hesitates so much it's hard to drive in heavy traffic.
  • billranbillran Posts: 113
    He might want to ask about this:


    If he asks about that specifically they should be able to find it. It looks like the TSB for 2005 was released in June 05 and perhaps at the time he asked it was either not yet available or not widely known about. I have read several very positive reports about the results of that TSB. Good luck!
  • I do not understand about TSBs. How comes the owner has to tell the dealer that a TSB exists for his/her car? Isn't the dealer suppose to have some responsibility to know what TSBs exist for which models? Perhaps if it is a safety-related bulletin they send out mailers to owners,,,, but they need do nothing on non-safety-related TSBs?? Who actually pays for the work done under a TSB? The dealer or the manufacturer? Maybe I am wandering off subject, but most drivers do not actively read this Forum. How would they know about the TSB?

    I think my idealism and optimism about a perfect world has just been tainted !
  • I agree: I have a lot of questions about the TSBs. It seems kinda cheesy to have to force the issue onto the Toyota dealer -- they obviously know there is a problem (complaint from my dad), there is apparently a fix available (TSB)...all they have to do is connect the dots. EIther they are lazy or deceptive, and neither is much good.
  • Way off subject: I have had a Ford Explorer for 8 years with the extended factory warranty. The Ford dealerships (several) that serviced the vehicle always seemed to check to see if there were any TSBs, since Uncle Henry was going to pay the dealer to exercise the TSB. I think the warranty repair and TSBs were a profit-making function for the service department. I appreciated the fact that Ford was taking care of me and my purchase. The vehicle has 140,000 miles and is working like new, except for a radio on/off button that turns "on" by itself. Maybe my vehicle has a resident ghost. . . . (more likely: dust in the on/off switch)

    If a dealership is getting paid to exercise the TSBs, you'd think that they would be happy to inform the owners of any new TSBs that apply to their vehicles.

    What am I missing ?
  • hylynerhylyner Posts: 216
    What am I missing? Funny you should ask.
    You may very well be missing the whole story.
    Rarely, when an original owner takes their vehicle to a dealership for service--advises a specific complaint--that the service dept. would fail to look up applicable TSBs for that complaint. The only exception would be a totally incompetent service dept, or some flukey failure to communicate by either party.
    It is my understanding that a policy such as described is one of the 'gospels' in the business, so it's difficult to believe this scenario either didn't happen as posted, or some really exceptional circumstances are involved which haven't been disclosed as yet.

    Speaking of "failures to communicate", I see that my proposed list of questions re hesitation got no response at all. That speaks volumes--it certainly answers some of my questions.
    Rather than dwell on it though, I'll just make a comment or two as a final note:

    When you go to a doctor looking for a solution to a problem--what's the first thing that happens? When you go to a lawyer looking for a solution, what's the first thing that happens? ......and so on. You get my drift.
    Just in case you are reluctant to answer, I'll say it anyway.
    The first thing that happens is the Q and A!! Every time!
    And for complex problems, more Q and A happens!!

    That's why I made the proposal re list of questions--because it hasn't really happened in this discussion--and it's fundamental.
    So somebody please tell us how it's proposed to find answers to the hesitation issue if there's a failure to communicate--ergo--no questions??

    What this profound (contrived??)silence tells me is that there's most likely little or no interest in finding solutions here.
    Either the discussion is little more than an enjoyable daily pastime for some, or the real objective is to cast aspersions upon an automaker.

    Like I said, if it's a sincere and honest objective to find solutions in any controversy, the the most important ingedient is a structured and objective Q and A.
    Why isn't something as fundamental as that happening here?
  • user777user777 Posts: 3,341
    agreed - i had the same question re: why noone else was willing to put up some green except myself and bettersafe to see to it that someone got a cool piece of hardware to get objective information about the phenomenon.

    contrived silence and aspersions? let's reel er back in.

    i think you've got the person with the problem that's interested in seeing that there's a fix, and you got the engineers that are theorizing about potential root cause. neither seem very interested in questionare design - but you do. so why don't you WAG one and present it?

    the design of it will have to be such that it captures quantitative information from a qualitative phenomenon with differing levels of understanding of the domain and of wording to describe what they are experiencing. the design will also have to be such that it doesn't lead takers down a path that is not appropriate.

    in my humble opinion - validity in questionaire design is orders of magnitude more difficult to achieve than slogging your way through hooking up an OBD-II interface and capturing some parameters while you repeat the phenomenon, after you figure out how it works.
  • wwestwwest Posts: 10,706
    "...proposed list of questions..."

    Q& not constructive.

    Because none of us know which question to ask next until we get a definite answer to the first question.

    Trouble-shooting any problem is like that, you need to explore logical "paths" with a Q&A series and so far none of the paths that have at first seemed like they might yield fruit have.

    Someone please remind me, what was the result of having an individual experiencing the delay disconnecting the battery each and every day?

    Until we can develope a cause and effect by reliably replicating the problem, virtually no progress can be made IMMHO.
  • hylynerhylyner Posts: 216
    I said "profound (contrived?)" Profound for sure, but contrived works, especially when it's already been openly advocated--several times BTW ! (Want some cutpasted examples?)
    I said either "fun for some, or aspersions" Either one works. No doubt about it IMO--it's either one or the other--or perhaps both.
    I've seen no evidence of any interest whatsoever in a process of finding realistic solutions, or using a structured approach to get there--starting with some meaningful questions.
    The way I see it, suiting the problem to a solution is the name of this game.
    I'd be happy to put together a matrix of good questions--but I'm quite confident it'll either be completely ignored, or one of the dedicated problem solvers will come forth with some "contrived" reason to refute it.
    So it boils down to a waste of time.
    BTW, I'd be happy to cough up the whole cost of an OBDII, but I can't help but think "Why bother?"
    I'm sorry, but this whole thing is developing a really distinctive aroma.....!
    That's my final answer. ;)
  • wwestwwest Posts: 10,706
    "...putting up some green...."

    I have already purchased the 2004 RX330 shop/repair manuals (~$600.00??) but even so I would be willing to participate in an OBD-II tool w/interface.

    1st question: Where, globally, is the person that is certain sure that they are experiencing the extended, hazardous type, engine/transaxle downshift delay?

    2nd question: Is that person capable of using the OBD-II, interface, and laptop to capture the sequence?

    3rd question: can we be sure that capturing the event will not be a long trial and error process?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 58,504
    TSBs: These are for dealer FYI. He is under no obligation to perform the TSBs or to tell you about them. Of course, it would generally be good business to do so, but nothing legally or contractually requires the dealer to do anything at all about TSBs if he choses not to.

    MODERATOR --Need help with anything? Click on my name!

    Share Your Vehicle Reviews Here

  • wwestwwest Posts: 10,706
    The accelerator pedal position sensors, two of them for redundancy, are both non-contact Hall Effect sensors. VPA is the sensor signal used to monitor accelerator pedal position and VPA2's signal is used to check for validity of the VPA signal. The two voltage outputs, VPA & VPA2 are displaced by at least 0.4 but not more than 0.8 volts. The actual displacement voltage between VPA & VPA2 is an on vehicle "learned" parameter.

    The shop manual seems to indicate that the accelerator pedal has some slack, dead space, backlash. The useable range is 0.8 volts (released) to 5 volts (fully depressed). With the pedal fully released the VPA output voltage can fall as low as 0.5 volts but it appears the ECU will not "take note" of pedal depression until the VPA voltage rises to at lease 0.8 volts.

    After the accelerator pedal assembly (includes sensors) is replaced the vehicle must be run for 15 seconds or more with no activity so the ECU can "learn" the new sensor voltage charactoristics. If there are no diagnostic indications after 15 seconds it is assumed the system is OK.

    The non-contact Hall Effect throttle valve position sensors, VTA1 & VTA2, work exactly the same except there is no backlash or slack. Throttle fully closed position is explicitly defined as 0.69 volts.

    With any persistent diagnostic indications concerning VTA1 & VTA2 the entire throttle body assembly is replaced (includes throttle valve, throttle valve drive servomotor and both hall effect sensors).

    A bit of a puzzle to me is that a new accelerator pedal, FULLY released, can have a VPA signal below (0.5 volts) the useable level (0.8 volts) or above (1.1 volts) the useable level and still be acceptable.

    Obviously a pedal assembly with a fully released value of 0.5 volts would exhibit some travel slack/backlash as it's being depressed before it reaches the 0.8 volt "useable" point.

    A puzzle.
  • billranbillran Posts: 113
    Not that it matters but I am an Engineer myself, albeit not an Automotive Engineer. I have to wonder what exactly the expected outcome of this discussion really is? Obviously, the Toyota Engineers would be the ones best suited to figure out why a very small percentage of owners report the hesitation. They apparently looked into it and issued a TSB which has been reported as very successful by many people.

    So, all that remains to be solved is why do a very few owners still report some hesitation after the TSB? At that point it would seem like you are certainly looking at a characteristic that applies to so few vehicles that the type of across the board theorizing you are doing here would not really apply.

    It seems to me like most of this discussion generally ignores that fact that very few owners even report any hesitation, and that a TSB exists that fixes the problem for many.
  • wwestwwest Posts: 10,706
    Are you really saying that automotive problems shouldn't be addressed unless LARGE numbers of drivers complain?

    IMMHO the really GOOD engineers are born problem solvers, will totally immerse themselves in a seemingly unsolvable problem.
  • alan_salan_s Posts: 362
    Could someone clarify please...
    I called my Toyota dealer last week and also opened a case with Toyota Customer Relations in CA over the transmission issue. Both the dealer and Toyota say that no TSB exists for the Avalon transmission and Toyota are "not aware of any other concerns regarding the Avalon transmission."

    Does TC004-05 ECM CALIBRATION: SHIFT FEELING ENHANCEMENT 2005-06-03 apply to the 05/06 Avalon?
    Someone suggested TC002-03 in the Avalon forum but nobody seems to know about that one either. The NHTSB and ALLDATA sites don't list either of these TSB's.
    If anyone has been successful, I'd appreciate the name of a dealer anywhere in the US or Canada who is aware of the TSB and has applied the TSB. I'll call them wherever they are.

    Thanks, all.
  • billranbillran Posts: 113
    wwest, not at all. But the fact that very few owners even report any hesitation, and that a TSB exists that fixes the problem for many, is a very important part of the equation.

    These are very relevant and important factors that for some reason seem to be consistently overlooked/ignored.

    I drive one of these vehicles everyday and it performs flawlessly. I would say that the vast majority of other owners who are not reporting any hesitation are experiencing the same excellent performance.
  • alan_salan_s Posts: 362
    billran you are indeed fortunate that your car does not have this problem. Mine is so irritating and unpredictable to drive in traffic, I'm to the point of dumping it.
  • billranbillran Posts: 113
    alan, I am sorry to hear that. I am not sure if there is a TSB for the Avalon or not. I did a quick search and did not see one right off the bat. I would think if that car had the same issue, and a similar cause, that one would be issued.
This discussion has been closed.