Last post on Nov 24, 2013 at 8:53 PM
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Toyota Sienna, Electrical, Van
#1 of 39 VSC sudden activation 2004 Sienna
Mar 01, 2011 (8:03 am)
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.
#2 of 39 Re: VSC sudden activation 2004 Sienna [spoore]
Mar 01, 2011 (9:14 am)
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.
#3 of 39 Re: VSC sudden activation 2004 Sienna [ateixeira]
Mar 01, 2011 (10:10 am)
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.
#4 of 39 Re: VSC sudden activation 2004 Sienna [spoore]
Mar 01, 2011 (11:15 am)
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.
#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?