VSC sudden activation. 2004 Toyota Sienna.

spoorespoore Member Posts: 9
edited October 2014 in Toyota
Has anyone ever experienced a sudden activation of the VSC system while driving under normal conditions? I was driving 65 mph on the highway going straight on dry pavement and suddenly a buzzer sounded, the VSC light came on, and the steering wheel and brakes were taken over by the VSC system and the car started weaving out of control. I could not steer or break the car. The car stayed on the road but weaved out of my lane, then the buzzer and light went off and I was able to pull off to the break down lane. My children and I were clearly in a life threatening situation. It happened again as I slowly got off the highway where I parked the car and had it towed to a Toyota dealership.

I am told by Toyota that the steering angle sensor needs to be replaced for $700.00. Still, I am terrified to drive the car.
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Comments

  • ateixeiraateixeira Member Posts: 72,587
    I was thinking bad sensor before you even mentioned it. Seems like VSC was kicking in when it didn't need to, applying brakes and forcing the van off the intended path.

    I think this is an "all or nothing" scenario, in other words, it would either work or fail completely, as you experienced.

    To be safe, ask the dealer to test it in situations where the ABS and VSC would have to activate, i.e. skidding scenarios.

    Glad to hear you were OK.
  • spoorespoore Member Posts: 9
    Thanks for your thoughtful reply. I asked the dealer to test drive it on the highway to make sure that it was no longer kicking in when it shouldn't, but did not think of having them check a real skid. I have been driving the car since 2004 and have never had the VSC kick in when slipping that I know of. If the light and buzzer goes on, then for sure it has never kicked in.
  • wwestwwest Member Posts: 10,706
    There are only 2 sensors unique to VSC, the stearing wheel rotational position sensor and the Yaw, lateral acceleration, sensor. This latter sensor is easily accessable to swap out while the stearing wheel sensor is not.

    Codes may have have informed the dealer as to which sensor had failed but I'm guessing not and the dealer chose the more profitable one.
  • ateixeiraateixeira Member Posts: 72,587
    If so, though, wouldn't they observe the same problem again on a test drive?
  • wwestwwest Member Posts: 10,706
    edited March 2011
    The stearing wheel rotation sensor is an "incremental" encoder (as opposed to an absolute position encoder) and as such will recalibrate itself, possibly even as you drive along.

    If you're driving along at reasonably fast pace and the yaw sensor is not indicating lateral, sideways, "turning" movement then the stearing wheel rotational position sensor can be safety "recalibrated" to zero, null, centered.

    So if the stearing wheel position sensor somehow became "out of calibration it would soon be re-calibrated.

    The Yaw sensor is hard mounted to the floor of the car somewhere near the "rotational", turning center. Let's say the sensor mount is loose, or the chip itself is loose in its mount and a good hard bump in the roadbed might move it askew and VSC activates as a result.

    Might it return to its original "mounted' position...?

    Maybe.
  • spoorespoore Member Posts: 9
    Wow, I am impressed by the knowledge you all have. I am now concerned however, that if it is the Yaw and they do not replace it, the same thing could happen again. Should I have them replace it too?

    I pulled up a Toyota Technical Service Bulletin online for the 2004 Sienna and Highlander that indicates that Toyota was aware that the steering angle sensor was causing "some customers to experience an intermittent VSC activation accompanied by the VSC light and buzzer". They changed the sensor February 2005 in all vehicles produced after that date.

    So, my read is that Toyota knew that this could happen to my vehicle, did not recall it or inform me about it, and put my family in danger. Am I right?? In addition, there are lots of other families driving around in a 2004 Sienna that don't know that this could happen, and their lives could be in danger. Not to be overdramatic, but it was really, really scary and could have caused a major accident.
  • wwestwwest Member Posts: 10,706
    edited March 2011
    TSB's are a bit of a strange "animal".

    The factory instruction to the dealer service personel is that the customer should NOT be informed of a TSB unless the customer first states a complaint which is covered by a TSB. Very few, if any, TSB's are valid outside of the warrantly period.

    The result of the above instruction is that dealer personel do not bother to read or review TSB's.

    So yes, Toyota quite willingly and knowingly put you and your family at risk.

    Under the circumstances I wouldn't worry about the yaw sensor.
  • spoorespoore Member Posts: 9
    As an update, the dealer replaced the part at no cost, test drove it on the highway, and I drove it today and so far so good. I expressed my concerns to the dealer over the fact that the TSB downplayed the risks and that the part was not recalled when they knew that many were defective. I checked the regulations and any defective part that affects safety is to be recalled by law. It seems like they got around that law by downplaying the risk. Any time that a driver can not steer or brake is a safety issue and I don't know how anyone could say otherwise. I worry about other drivers out there that could get in an accident, and about why Toyota isn't worried about these families. I won't purchase another car without an override button. I also will not buy another Toyota. Thanks for all your help!
  • spoorespoore Member Posts: 9
    I have another question....if the VSC takes over the car again (and for other 2004 owners who may have this happen to them), what should we do to gain control of the car? I could not brake or steer, so it seems like my only options are to put the car in neutral or shift down, although it is an automatic. A friend told me to take the key out of the ignition, but wouldn't doing so cause other problems?
  • wwestwwest Member Posts: 10,706
    edited March 2011
    ".. I could not brake or stear..."

    Are you sure of that..? I don't know of any VSC activaton mode, nor of any TC(TDC) mode, that would actively interfer, in any substantive way, with either braking or stearing.

    VSC activation functions are such that although disconcerting you should be able to easily maintain control of the vehicle.

    If VSC engages inadvertently in "plowing", understearing mode, it will instantly dethrottle the engine and apply moderated (ABS "pulsing") braking to both rear wheels.

    If VSC inadvertently activates in over-stearing mode, thinks the rear is trying to outrun the front, it will instantly dethrottle the engine and apply moderated braking to the proper front wheel.

    But IMMHO if this were to occur inadvertently on a low-traction, icy, road surface it would be, potentially, a life-threatening circumstance/experience.
  • spoorespoore Member Posts: 9
    The steering wheel was going from right to left, was that happening because alternate braking was happening or is there a mechanism that takes over the steering wheel? For example, to help one steer out of a skid.

    I could not slam on the brakes on the highway, but if I was going slower, could I have overode the fact that the pedal was going in and out on its own?
  • wwestwwest Member Posts: 10,706
    edited March 2011
    It sounds as if VSC was "thinking" that you were over-steering first to the right and then to the left then to the right, etc, etc. That would result in alternate application of the front brakes, right, then left, then right, etc.

    What you were feeling on the stearing wheel would probably be comparable to fairly serious torque stear, nothing an average person couldn't overcome with a firm grip. Same with the brake pedal, it would have felt as if ABS were activated. VSC would rarely use firm braking, if ever. What you felt on the brake pedal was "moderated" braking using an on and off pulsing mode such as happens with ABS activation.

    As long as VSC was inadvertently activated it would continue to modulate the brakes, but that would not mean full braking force wouldn't be available if you attempted to make use of them in that manner.

    These are questions that really should be asked of the technical advisor at your Lexus dealer.
  • busterlandbusterland Member Posts: 1
    My wife and I both had the same experience with our 04 Sienna. Thankfully we were both driving 30 mph or less. I actually had to drive the car for the dealer to prove it was happening. I'm appalled that Toyota is not standing behind an obvious defect. What would have made this a recall? A death? I was told the same $700 price tag, however, I plan to complain to every regulatory agency I can find to get a refund. Toyota should be ashamed of their poor customer service and indicted for putting Americans at risk from unsafe vehicles, that they are aware of as being unsafe. Not only will I never purchase another Toyota, I will tell my friends and anyone that will listen that they should steer clear of any Toyota product.
  • spoorespoore Member Posts: 9
    My understanding is that any defective part that poses a safety risk is to be recalled by law. Toyota clearly downplayed the safety risk and got around the law. Scary, and tells me that Toyota puts profits over safety and I will never purchase another one.

    They did not end up charging me the $700 and I filed a complaint!

    I am glad you are okay, that is the main thing.
  • deniser3deniser3 Member Posts: 6
    This just happened to me yesterday with a 2004 Sienna, very scary thing and Thank God we weren't on the highway. The van is at Toyota right now and they want to charge me $895 for the repair. I called to express my concerns several times and to share what I found here. They also are aware now of the TSB and checking with their Toyota "rep" to see what they can do. Hopefully this will be a no charge repair...we will see tomorrow since they have to order the part and I have no vehicle for another 24 hours. Gave me the "not under warranty" line, but I bought this van, used with only 20,000 on it from this same dealer so I hope they do something for me. What a nightmare.
  • lfrescaslfrescas Member Posts: 1
    The same thing happened with my 2004 Sienna a few months ago. We took it in, and I even presented the TSB info, but they said it was a steering column sensor, charged us $800 to fix it and sent us home. Well, it happened again this morning. Anyone have any suggestion on a course of action to get this fixed correctly? We were about to leave on a 700 hundred mile trip to see my mother with kids in tow, and on the highway this would have been frightening.

    And to back up what the other person prior to this said... it does, actually, feel like it cannot be controlled. Now, it could be my panic taking over because the car is fighting me for control, but I found it nearly impossible to drive when the issue was happening, so AAA had to tow me in when it initially happened. This time, my husband is going to try and drive it there.
  • deniser3deniser3 Member Posts: 6
    edited April 2012
    WOW, can't believe the problem wasn't fixed and it is back, that is frightening. Could there be a sensor for each tire and they only replaced one? I ended up paying $580 after much whining. Seems they should give you a rental van for your trip? Good luck and please post what happens!

    You are right, it does feel like it's out of control. I found letting the van sit for a few hours "reset" the issue and I was able to drive it to Toyota without it happening.

    Oh, and please be sure to call the 800 toyota number and provide all your information. They are tracking this issue in their system and I was told if enough people have the same problem it could turn into a recall. And if that happens I would be re-imbursed what it cost me to fix it.
  • whfh99whfh99 Member Posts: 3
    My wife just experience this issue with our '04 Sienna last week. Low speed, thank goodness, and caused the vehicle to pull so far to the right that it hit the curb and destroyed the tire. We had to have it towed. Can anyone reference the service bulletin online and what steps were take to get this addressed? I am frankly shocked that such a defect could occur. I would have thought that there would be fail safes in this system that it would deactivate itself vs. actively put the occupants in danger. Please, any more links or references to try and learn more about how to know for sure what the problem is and how to fix would be great. I'd like to see Toyota take care of this on their time and welcome the 'ammunition' to have when I speak with them.
  • wwestwwest Member Posts: 10,706
    There are only 2 sensors "unique" to VSC, a stearing wheel rotational position sensor and a lateral accelerometer, YAW, sensor. If one of those fails in an undetectable way you will get VSC activation.

    Engine dethrottling and rear braking (slow this sucker DOWN) if the system defaults (on failure) to understeering recovery/correction. If it defaults into oversteering recovery/correction mode you still get engine dethrottling but braking ONLY on ONE front wheel.

    Obviously this latter scenerio could prove to be the more dangerous.

    You can remove the ABS pumpmotor fuse to disable TC, VSC, etc, but that alos disables ABS.
  • whfh99whfh99 Member Posts: 3
    Thank you. Sounds like we had the oversteering recovery issue as the braking was on JUST the right front wheel at low speed. Do you happen to know where and which fuse that is? Might be the safer option until we get this looked at? Nothing wrong with driving 'old school'. Do you know if the dealer has diagnostic tests that can definitively determine if one or both of these sensors are faulty? I want to avoid spending money for them to guess or replace parts just for something to do on my dime. Also, heard there was a TSB out there and some people got Toyota to cover the repairs? Anything I can print and bring with me would be helpful.

    Link
  • spoorespoore Member Posts: 9
    I did find a service report on line and I printed it out, took it to the dealer, and did not have to pay for the replacement part or service. I made a big deal about the fact that they are fully aware of a dangerous defect and made a conscious decision not to recall the part. I can't find it but will search when I get home tonight.

    I now own a VW with an override button. I would not purchase another car without one due to my experience with the Sienna.
  • fibber2fibber2 Mid Hudson Valley, NYMember Posts: 3,786
    edited October 2012
    I didn't realize that people were still having unresolved problems with this, or I would have posted these links to my cloud site earlier.

    http://www.mediafire.com/view/?x97fu482azyi9c3

    http://www.mediafire.com/view/?vy8d4wxoglx4yde
  • whfh99whfh99 Member Posts: 3
    Thank you for sharing this information. Guess I'll have to get the vehicle scheduled for service and see how it goes.
  • aichingeraichinger Member Posts: 5
    Hello,
    I am having the exact same issues with my 2004 Sienna AWD XLE. Can you give me more details on your specific Sienna, was it an AWD, what was the VIN, did you even having any similar issues before?

    I am not using the drive flat tire Toyota originally delivered. They wear out too fast and cost too much. I have been told that I need to change to drive flats, but am unconvinced as I have not had the issue during 4 sets or normal tires (Michelin and Parrelli).

    Thank you for your help.

    Regards,

    Peter Aichinger
  • aichingeraichinger Member Posts: 5
    Hello,
    I am having the exact same issues with my 2004 Sienna AWD XLE. Can you give me more details on your specific Sienna, was it an AWD, what was the VIN, did you even having any similar issues before?

    I am not using the drive flat tire Toyota originally delivered. They wear out too fast and cost too much. I have been told that I need to change to drive flats, but am unconvinced as I have not had the issue during 4 sets or normal tires (Michelin and Parrelli).

    Thank you for your help.

    Regards,

    Peter Aichinger
  • aichingeraichinger Member Posts: 5
    Hello,
    I am having the exact same issues with my 2004 Sienna AWD XLE. Can you give me more details on your specific Sienna, was it an AWD, what was the VIN, did you even having any similar issues before?

    I am not using the drive flat tire Toyota originally delivered. They wear out too fast and cost too much. I have been told that I need to change to drive flats, but am unconvinced as I have not had the issue during 4 sets or normal tires (Michelin and Parrelli).

    Thank you for your help.

    Regards,

    Peter Aichinger
  • aichingeraichinger Member Posts: 5
    Hello,
    I am having the exact same issues with my 2004 Sienna AWD XLE. Can you give me more details on your specific Sienna, was it an AWD, what was the VIN, did you even having any similar issues before?

    I am not using the drive flat tire Toyota originally delivered. They wear out too fast and cost too much. I have been told that I need to change to drive flats, but am unconvinced as I have not had the issue during 4 sets or normal tires (Michelin and Parrelli).

    Thank you for your help.

    Regards,

    Peter Aichinger
  • spoorespoore Member Posts: 9
    Peter,

    Yes, it was AWD and I too switched to regular tires (the tires were not the problem). I found a service notice that was issued by Toyota to its service staff online, that made it clear that they were aware of the defect but it was not regarded as a threat of injury so was just a notice to service, not a recall. In other words, the cost of potential injury and replacement of the part was on the owner. I marched that document to my Toyota dealer and demanded it to be fixed...and they fixed it free of charge. I was extremely upset as I was driving at 65 mph on a very busy highway with my kids in the car when the car went into protective skid mode even though the road was dry and I was traveling straight down the road. We avoided an accident but it was scary to say the least! I sold the car and now drive a VW with a shut off switch for the VSC. I feel much safer.
  • fibber2fibber2 Mid Hudson Valley, NYMember Posts: 3,786
    When you got new tires, did you also get a wheel alignment? Too many independent shops still haven't gotten the word that you MUST do a system reset after a wheel alignment to compensate from the change in tire angle with relationship to steering wheel angle. It doesn't take much of an angle change (a degree or so) to inadvertently trigger the VSC system. If an alignment places the angle near the edge of range and you hit a bump or have any natural drift at all, it's going to engage. See the links I posted a page back.
  • stevemvstevemv Member Posts: 5
    edited August 2013
    Hi, I have a 2004 AWD Sienna XLE Limited (bought it new in 2003) and the VSC problem started about 6 months ago. Happens when going downhill on a curve...two times at 65 mph or so and once at 35 mph. All seemed to be when I was turning right slightly and all happened on perfect road and weather conditions. Car beeped, VSC light came one, the van slammed on the brakes and pulled right. Scary as I was next to a semi one time. Don't want my wife driving the van now. I talked to another Siena 2004 owner and he had same issues and he had no luck with the dealers in our area...they could not duplicate! He spent a lot of money on new tires and front-end work to no avail.

    Anyone had any luck with Toyota directly or a dealer? it is a safety issue pure and simple.

    Thanks,
    Steve 8/29/13
  • stevemvstevemv Member Posts: 5
    Peter,

    Any update?

    stevemv
    2004 Siena owner with vsc problem too!
  • aichingeraichinger Member Posts: 5
    Sorry, I have been traveling and did not respond.
    First, I would like to say I just want my car to work and am not looking for more. I am concerned that some may be fishing for some kind of settlement.

    The Toyota dealer in Lompoc CA at first indicated that the Toyota rep had identified some cases where they stated using run flat tires was the problem. I have run multiple sets (3) of non run flats without problem, so I discount this diagnosis. I did have a case a couple of years ago when the car would apply the ABS when driving at speeds greater than 20 mph or so. At that time I disconnected the ABS relay and drove to the dealer (where I reinstalled it). The dealer said the steering wheel sensor needed calibration. I had never done this and had aligned the wheels frequently, given that I have an AWD which "ate" tires. This corrected the problem for 3 or 4 years.

    The dealer told me that Toyota told them that I needed a new steering rack. It would be $800 with no guarantees. The steering is very good with no wandering and no wheel play. So I have a hard time believing this. I would spend the $$ right away if it would fix it, but do not want to start throw money at this with no diagnosis.

    There are only a few components which are in question.
    1. The ABS wheel sensors (also tells ABS if wheels are locking)
    2, The Steering sensor (needs to be calibrated to the steering shaft)
    3. The yaw sensor (tells if the car is rotating as during a skid)

    That's it! All of these have fault detection built into the car. It nothing shows up as a fault they are most likely working at least to some degree.

    The dealers said they looked at everything, but I do not have the confidence that more was done than plugging in the OBD II.

    1. The ABS sensors can be viewed easily with the wheel off. I need to check the sensor and the splines on the shaft (which others have found can get rust and dirt in them as well). ABS sensor are about $90 each without install.

    2. The steering shaft sensor can be easily re-calibrated through the ODB II connector. There is a Toyota Service Bulletin (TSB) on this and it is doable by a home mechanic.

    3. The yaw sensor appears to be the tough one. No east test and very expensive. If all else fails I my go to a junk yard and see if a swap helps.

    Once the ABS sensors have been checked/replaced/ the steering sensor re calibrated and even the yaw sensor swapped there is little more which can be done.

    In the final analysis this could be a systems issue (yes, I am an engineer). In the case of a systems issue, all the combined sensor tolerances my not be working out. Several parts must all play together for this system to work. If it was not designed correctly the errors stack up up and the system fails to function properly even though the individual parts are working to the manufacturers specifications. A classic design failure for many systems.

    We should all be mad as hell! Looking on the National Highway Traffic Safety Admin. site (NHTSA) there are several reports of this same issue. It is CLEARLY a SAFETY ISSUE (and this on what was a $35K car)! We also face some really bureaucratic gov policy at the NHTSA. The definition of what gets recalled is vague at best.

    Beyond this there are numerous complaints by people like us listed on line. Toyota indicated they do not recognize what people put in chat rooms, but most of us have gone to the dealer as well. They are clearly aware that this is an issue.

    When I told this to Toyota Motor Sales (I called it in), I was told that there is no recall in place.

    I will work through my "punch list" to see if I can fix this myself, but would really like to escalate this. We would need reference to as many owners who have this problem and the car VINs. Everyone should make certain to file a complaint on the NHTSA site as well as will Toyota Motor Corp. The NHTSA reacts well to consumer pressure and I would go directly as well as through my local political representative.

    Please let me know what everyone else finds.

    Regards,

    Peter
  • stevemvstevemv Member Posts: 5
    Thanks Peter for the update,

    I will file complaint on NHTSA site and I will be talking to the dealer serv mgr next week. Also, I removed run-flats years ago from my AWD Siena as they chewed them up way too fast.

    stevemv
  • roadsetrroadsetr Member Posts: 2
    Hello I have this problem too and it is very annoying. I have spent lots of money changing tires to fix it but it did not work. I am prepared to go to toyota to have them fix this I printed the 2 mediafire links for the yaw sensor and zero point calibration. Should I print any other things? I could not find a service report. Also what should I tell them when I get there. Because every time I try, they just change tires and I have to pay, while nothing happens.

    Thanks
  • stevemvstevemv Member Posts: 5
    We brought our van to the dealer, they adjusted some sensors and I am not sure what else. They did not charge me for this cause I spoke with the service manager ahead of time and complained.. I am not confident the issue is fixed but it has not happened to me since that servicing over the last two months.

    We just traded the van in for a new vehicle, so I hope everyone gets their issue resolved with their Sienna.

    stevemv
  • fibber2fibber2 Mid Hudson Valley, NYMember Posts: 3,786
    I'm sure that they just did the Zero Point Calibration procedure, and all was fixed. If you had no further problems, then they finally did it right! Best of luck with the new vehicle. What did you get?
  • stevemvstevemv Member Posts: 5
    Kids all grown...mini-van days finally OVER!
    Got a Lexus IS350...very un-minivanish! :o) bery fun car...

    Thx
  • roadsetrroadsetr Member Posts: 2
    wow, thanks for the fast responses. I just want to makes sure my problem is the same as the other ones here. Sometimes in the middle of the road and highway, the car beeps and does a couple brakes. This process takes about 3-5 seconds. Also the light with the car and the curved lined behid it turns on. this is what i mean
    http://cdnedge.vinsolutions.com/dealerimages/Dealer%202812%20Images/trac-inop-li- ght.jpg
    I just wanted to make sure that this is the right place to look at and that i have the same problem as you guys

    thanks again
  • chief5902chief5902 Member Posts: 1

    I just bought a used one from private seller !  And it did the same thing , the vsc activated !!! The brakes were on and the engine got slower 

  • knownspaceknownspace Member Posts: 1
    Hi Steve. Did you find a cause of the intermittent VSC activation? I too have the exact problem showing up in my 2004 Sienna and am trying to get more information before I take it in to the dealer. Thanks.
  • amanoamanoamanoamano Member Posts: 1
    we have an 05 this happens to us for about 2 years getting worse now it happened on the freeway
    terrifying van at toyota now replacing rack and pinion assembly completely $1500.00!

    i will let you know if it fixes we did unplug the plug under hood but it only helped for a few weeks
    dont recomend following that route was told a few times by different dealers it could be rack and pinion
    note :
    the YAW sensor may or may not fix it you are right though
    toyota is ignoring this until someone dies if not already happend. my opinion only of course 11/ 25 /2015
  • pilbaraboundpilbarabound Member Posts: 1
    I have 2 AWD Sienna's one a 2006 and one a 2004 both have just recently started locking up, with no warning, especially dangerous living in the San Bernardino mountain... We've had it into the dealer, they kept the 06 for nearly 2 weeks, the Toyota service manager drove it home for a few days...
    They reset the sensors (Yaw I think!) and they did a few other things, told us it was good to go, we drove it back up to Lake Arrowhead and it locked up twice on the way up.

    Back to the dealer, this time the problem was caused according to them because we had mis-matched tires on, they suggested replacing all four tires, which we did, stayed away from the run flats... which the service manager said was ok $812 later we drive up the mountain does exactly the same thing.

    Back to the dealer, they keep it for 3 days then come up with the fact that we need to have the original Run Flats and thats why the thing is locking up...

    Doesn't make any sense to me, we have video of the vehicle locking up on straight highway, but they still maintain its because we don't have run flats on it... Any advise would be appreciated, don't want to run out and buy another new set of tires if it's not going to fix the issue...

    Thanks
  • jwhitt1jwhitt1 Member Posts: 1
    edited December 2015
    I have had this issue for about 2 years now but interestingly enough it has only happened in a certain part of the state far from my home when I visit friends about twice a year. Until last week, it never happened where I live including freeway driving. Finally happened at home driving at 30 mph and 5 times today on my way up to visit same friends in NorCal. I get a series of beeping and skid control light goes on. Brakes pump on their own and car pulls either right or left depending on the turn. A firm hand on the wheel keeps me under control and I have never left my lane but it is hair raising and aggravating. The whole scenario lasts about 2-5 seconds. Sometimes it only beeps with no braking. Haven't been to dealer yet but have had my tire store replace tires, wheel sensors, etc. Like others, I replaced my run flats with normal tires. Glad I came upon this site to know I am not alone. When I get back home I'll have a little talk with the Toyota dealer. My wife and I sold our older Ford Windstar for this brand new 2004 Sienna and I have regretted it for years. First the shock of the cost for run flats, then the auto slide doors stopped working and Toyota only wants about $2k per door to replace door motor, drivers seat warmer stopped working long ago.....I could go on but now I'm starting to get pissed off again. No more toyotas for me. Fortunately my kids are old enough now that we no longer need a minivan......good riddance.
  • wprowsewprowse Member Posts: 1
    Hi, I've read a lot of these complaint on the Sienna. One thing I've noticed, even on professional diagnostic websites, that no one hows recorded live data. The first thing I checked was the live data for the steering sensor. First thing I noticed was the sensor reading was stuck at 1150+. Which would tell the computer that your over steering. The thing that doesn't make since is that with the steering wheel, with working sensor, will only few degrees passed 500, positive or negative. I would think the computer would show a trouble code. Anyways I went even further. I disconnected the steering sensor. The computer still shows 1150+ without a trouble code. So I back probed the steering sensor. Shows to be functioning properly. I performed recalibration of steering sensor, yaw sensor, etc. per Toyota's instructions. I did this four times and only after the fourth time, the steering sensor ready became normal. It would go from a little over 500+ to 500-, worked normal. So I thought that everything was okay. I test drove and watched the live data of the steering sensor. Worked perfectly. So drove to the shop and parked it, turned it. Came a little later just to check and be sure the problem was fixed. Hooked up my scan tool to check steering sensor live data. Stuck back on 1150+. So just to be sure it wasn't a fluke I did the recalibration again. After the fourth time steering sensor read normal. But of coarse after shutting off the vehicle back to 1150+. I'd like to fix this and been working as a mechanic for over 25 years but, this one has me stumped.
  • 41dash4141dash41 Member Posts: 1
    I have a 2005 Toyota Sienna where the vsc system activated and slowed our van down. When it first happened we thought that the van broke down because there was a beeping sound and it seemed like the brakes activated by itself. Kinda scared us because we were going around a turn at 35mph We then noticed that the system activated every time around the same turn and we prepared ourselves every time we went around that turn. We tried going at different speeds and 90% of the time it activated at the different speeds. I read up on what the vsc system does and now the vsc activated at a different location that scared us again because we were going 60mph. Tried searching for possible causes for the activation on the internet. I noticed that all of the activations are on left turns. Was wondering if a bad suspension would activate the vsc system? Maybe the van is tilting past an acceptable angle on the turns and the system senses that?
  • fibber2fibber2 Mid Hudson Valley, NYMember Posts: 3,786
    edited February 2016
    Remember that the system tracks the steering angle (how much you rotate the steering wheel) with the actual arc that the van takes on the road. Things that can make the system think something isn't right and that it has to intervene to prevent a possible crash are:

    1) Basic setup calibration. The Zero Point calibration sets the steering position sensor and the yaw (leaning and lateral acceleration) sensor in sync.

    2) If the tires were to slip sideways (wet road, crappy tires) the system would see this as understeer. I would think that an off-camber turn might accentuate this.

    3) Worn wheel bearings, suspension components - same. The input won't match the output. Combine this with #2 and you will get a much wider turn than the steering angle would predict.

    As an engineer, I'm more apt to look at the data and try to 'adjust' if you can't come to a more professional diagnosis and permanent fix. For instance, if the problem ONLY happened on left turns and was predictable in occurrence, I'd skew the calibration setup ever so slightly to favor the left (offset the yaw or steering sensor towards left bias) so that it was more 'centered' for the new reality. You might also simulate this by adding a few psi of air pressure to the right two tires and take this same curve and see if it helps. But remember this is just a suggestion - proceed with experiments at your discretion!
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    If you all had to speculate, what might you offer as a "root cause"? If calibration and "adjusts" don't fix it, what's the conclusion?
  • thecardoc3thecardoc3 Member Posts: 5,427
    He's not far off in some ways. A steering angle sensor recalibration might be in order if it is out. That calibration is a critical input for the VCS system and when it is out it can cause false activation of the system. With my factory Techstream scan tool, or even my Snap-On Solus Ultra the first step would be to see what the steering angle sensor is reporting when it is in the straight ahead position as well as retrieving any trouble codes from all of the modules on the vehicle. The steering angle sensor recalibration is performed with those same scan tools and is a normal routine to carry out for most shops.

    The one thing that should NOT be done is attempting to change tire pressures or "adjust" the sensor or its output to anywhere other than where service specifications require.
  • fibber2fibber2 Mid Hudson Valley, NYMember Posts: 3,786
    edited February 2016
    My suggestion was as a diagnostic aid, and not as a 'fix'. However, if you've totally exhausted all reasonable options and no amount of money thrown at the van has solved the problem (like replace EVERYTHING), you may have to adjust to compensate.
  • eeguru6677eeguru6677 Member Posts: 3
    I know your pain. Toyota and their dealers do too, but is waiting for it all to die out - the cars, the owners, they don't care as long as they save a buck (check the Unintended Acceleration case they recently lost).

    After running into this a few years ago while touring Yellowstone (real scary on mountain roads with switchbacks), this became a constant issue. It is real dangerous when it happens at 75 mph on the interstate with trucks on either side of you!

    I ran into a thread that talked about there being a problem with the bushings on rack and pinion module, and that seems to fit well with the data. There are rubber bushings on the module mounting and they deteriorate after a while and must be replaced. So I replaced mine, but the problem still happens - I have a few areas where I can make this happen at will. I finally disconnected the yaw sensor under the seat - no VSC, no ABS, no nothing! At least the car does not try to kill its drivers any more.

    Last night I looked under the car while my son rotated the steering wheel and noticed that the rack still moves when rotated - the bushing issue is still there! I am replacing that ?@#$@#$? $500 rack to see if that helps. If nothing else, it should tighten up the steering. Then a front end alignment and resetting of the VSC system. Will let you know what happens.

    PS - The AC system on the 2004 Sienna sucks also!
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