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VSC sudden activation 2004 Sienna

spoorespoore Posts: 9
edited December 2013 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.


  • ateixeiraateixeira 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 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 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 Posts: 72,587
    If so, though, wouldn't they observe the same problem again on a test drive?
  • wwestwwest 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...?

  • spoorespoore 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 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 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 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 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 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 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.
  • 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 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 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 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 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 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 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 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.

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