Last post on Nov 24, 2013 at 8:53 PM
You are in the Toyota Sienna
What is this discussion about?
Toyota Sienna, Electrical, Van
#5 of 39 Re: VSC sudden activation 2004 Sienna [wwest]
Mar 01, 2011 (11:21 am)
If so, though, wouldn't they observe the same problem again on a test drive?
#6 of 39 Re: VSC sudden activation 2004 Sienna [ateixeira]
Mar 01, 2011 (12:44 pm)
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...?
#7 of 39 Re: VSC sudden activation 2004 Sienna [wwest]
Mar 01, 2011 (1:31 pm)
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.
#8 of 39 Re: VSC sudden activation 2004 Sienna [spoore]
Mar 01, 2011 (6:26 pm)
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.
#9 of 39 Re: VSC sudden activation 2004 Sienna [wwest]
Mar 03, 2011 (11:30 am)
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!
#10 of 39 Re: VSC sudden activation 2004 Sienna [spoore]
Mar 06, 2011 (6:07 am)
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?
#11 of 39 Re: VSC sudden activation 2004 Sienna [spoore]
Mar 06, 2011 (10:55 am)
".. 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.
#12 of 39 Re: VSC sudden activation 2004 Sienna [wwest]
Mar 06, 2011 (1:44 pm)
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?
#13 of 39 Re: VSC sudden activation 2004 Sienna [spoore]
Mar 06, 2011 (11:20 pm)
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.
#14 of 39 Re: VSC sudden activation 2004 Sienna [spoore]
Mar 15, 2011 (5:46 pm)
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.