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Vehicle Stability Control

Discussion in 'Gen 2 Prius Technical Discussion' started by Walt999, Dec 24, 2009.

  1. Walt999

    Walt999 New Member

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    Can VSC be turned off on 2007?
    Walt
     
  2. qbee42

    qbee42 My other car is a boat

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    No, and nor would you want to. VSC is a very important safety system. There are only two reasons to ever disable VSC (if you could):

    1) Racing.

    2) Doing donuts in a snowy parking lot.

    Tom
     
  3. dogfriend

    dogfriend Human - Animal Hybrid

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    VSC is the bomb. It saved me once even though I'm usually a very conservative driver.

    My GF's 2001 Avalon has a switch to turn off the VSC, but we have never had a reason to use it.
     
  4. BAllanJ

    BAllanJ Active Member

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    I bet he means traction control... there's no need to even want to dissable vsc unless you're trying to teach your kid how to get out of skids in regular cars...in which case, use a regular car.

    If you want to dissable tc, you can (do a seardh on maintenance mode) but you're risking your motor if you do that.
     
  5. qbee42

    qbee42 My other car is a boat

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    Most likely that's it. People get those two mixed up all the time.

    Tom
     
  6. Walt999

    Walt999 New Member

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    No, I mean VSC. The reason is that my 2007 has a steering problem at hi-way speeds and I wanted to make sure that the VSC wasn't sending messages to the steering motor that would interfere with the normal steering function.
    I now have the procedure but haven't tried it yet.
    I just got a case number from Toyota and an appointment at the dealer tomorrow -- but I'm not holding my breath that they will be able to fix it. This is my third try. I'm not sure whether any of Toyota's dealer service departments are fully qualified to diagnose and fix the Prius.
    Time will tell.
    Walt
     
  7. Bob64

    Bob64 Sapphire of the Blue Sky

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    Check alignment. It could also be high winds blowing your car around. I think theirs a post around here that recommended getting some of the tires toe in or something to mitigate the your problem.

    I've also heard that new tires can also help.
     
  8. dogfriend

    dogfriend Human - Animal Hybrid

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    +1. Especially check rear alignment. The dealer may not want to deal with the rear alignment because the "official fix" is to replace the axle beam, but I was able to shim mine successfully to fix it.

    See here for a thread I hijacked on 2007 Alignment:

    http://priuschat.com/forums/gen-ii-...ooting/33373-2007-model-alignment-issues.html
     
  9. qbee42

    qbee42 My other car is a boat

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    I will be very, very surprised if VSC has anything to do with your highway steering issue. When VSC kicks in, it cuts power and applies individual brakes as needed. It doesn't send steering commands to the power steering system.

    Is your highway steering issue new or have you had it all along? What type of tires are you running and at what pressure? How many miles on them?

    Tom
     
  10. ken1784

    ken1784 SuperMID designer

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    I believe the VSC warning will be ON when VSC detects something.

    Ken@Japan
     
  11. dogfriend

    dogfriend Human - Animal Hybrid

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    Yes, when VSC kicks in there is a warning lamp + audible warning tone.
     
  12. Walt999

    Walt999 New Member

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    Thanks everyone. I understand why the VSC/Traction control/ABS system should not be disabled because it also would disable the protection it provides to the drive system.
    I had my dealer do an alignment but his work was questionable. He didn't measure caster (could help detect if something is damaged or bent -maybe the car was dropped during shipping and unloading). There is more camber on the left side than the right side, but still winthin specifications. He set the toe to a total of zero, but -0.1 left and +0.1 right. And the rear showed horrible differences left to right, but again within spec. This could have been due to careless positioning when placing the car on the "drive-on" type of alignment machine.
    I bought the car used - a nice clean 2007 with only 14,000 miles and it drifts all over the road even on windless days. It seems to be overly sensitive to the crown on the road. The steering is whatI I consider stiff and unresponsive. By that I mean that when it drifts one way or the other and corrective pressure is applied to the the steering wheel, nothing happens until increasing the pressure to point where it starts to correct the drift -- and then it over-corrects and heads off to the other side. It takes constant steering correction and after about 200 miles I notice both physical and mental fatigue that I have never experience with another vehicle.
    I've owned 5 motor homes from 22 to 30 feet in length and have never felt fatigued from steering even in such large vehicles.
    I have a case number from Toyota to have another dealer look at it but scheduling got screwed up because of the Holidays so I'm still waiting.
    The tires are the original with little wear and no sign of feathering or uneven wear from camber.
    So -- I'll report back if and when Toyota does anything.
    Walt
     
  13. dogfriend

    dogfriend Human - Animal Hybrid

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    When my rear alignment was messed up, it reminded me of towing our travel trailer. I noticed that different amounts of steering were needed between turning right and left, and I would tend to overcorrect when turning one direction. Shimming the rear to get equal toe in at the rear helped immensely.
     
  14. DeadPhish

    DeadPhish Senior Member

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    TC cannot be turned off because it's part of the very essence of the Prius soul! How's that?

    The revolutionary THS ( Toyota Hybrid System ) back in the original Gen 1 Prius allowed the electric motor to drive the wheels at times in order to assist the ICE. For example at start up from a stop light.

    However what they knew is that electric motors have maximum torque from RPM number 1. Other vehicles have to get rolling and rev the ICE up to 2000 or more likely 4500 RPMs before the max torque kicks in.

    The Prius has Max Torque as it's sitting still at a stop light. It's so strong that without a damper on the wheels ( Ta Da ) in the form of Traction Control you or I would hit the GO pedal and our tires would begin to scream and start smoking as the Prius attempted to rip away from the light like a funny car at a drag strip.

    To solve this minor issue :eek: the engineers built Traction Control into every Prius from the very first one onward. In fact you can't drive efficiently without it. The e-motors are too strong for the vehicle.
     
  15. DeadPhish

    DeadPhish Senior Member

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    Yes you need to keep investigating but one your comments leads me to another characteristic of the Prius which is usually unknown before it's been driven quite a few miles.

    The Electric Power Steering is uber sensitive. There have been a lot of comments since the first Gen 2s came out that the vehicle drifts and wanders and can't be kept in a straight line. The EPS is very sensitive, there is no play in the wheel at all. Brush the wheel with your coat and it will go left or right.

    In fact it is a characteristic of the Prius that needs some adaptation by the driver. It doesn't drive like prior vehicles did. More and more vehicles are going the EPS route because they're simpler, lighter and more accurate ( IMHO ). But they do need constant attention when driving.

    I've shifted from having one hand at Noon or 11:30 to a couple of fingers at 6:00. It's more restful and it holds the vehicle straight and on course.
     
  16. Walt999

    Walt999 New Member

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    My steering at hi-way speeds is anything but sensitive. Also the steering effort is so high that you cannot easily steer with two fingers. It takes a minumum of a firm grip on the rim of wheel with at least one hand. i've wrestled with this car for approx 4000 miles and it does not respond properly.
    I've been driving for over 70 years, all kinds and sizes of vehicles from pickups, buses, small cars, large cars, and sport cars.
    I've RVed for approx 700,00 miles in the past 35 years pulling all kinds and sizes of trailers and five motorhomes ranging in size from 22 to 30 ft. in length.
    Of the last thirty or so vehicles that I have owned, this car is by far the poorest steering over-the road-vehicle that I have had.
    It is not a case of getting used to it. There is a problem that has to be addressed.
    Still waiting on Toyota,
    Thanks for your thoughts,
    Walt
     
  17. qbee42

    qbee42 My other car is a boat

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    This isn't right. At highway speeds, all you need to do is *think* about steering and your Prius should start moving. I drive my 2006 with fingertip pressure. You definitely have a problem. I'd start by looking at the tires.

    Tom
     
  18. DeadPhish

    DeadPhish Senior Member

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    In this case it's probably your personal vehicle then. As qbee42 noted just above the waves from your eyelash blinking will deflect the steering slightly. Having to fight it to turn would then seems to indicate that there might be something amiss in yours which needs local attention.
     
  19. vertex

    vertex Active Member

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    Yesterday I drove 100+ miles for the first time in my 2006 Prius. I must say that the VSC and ABS etc. did an excellent job of keeping the vehicle going straight down the road. I was driving on the Taconic Parkway down from Albany. For those of you that aren't familiar with the road, it is a 4 lane (2 each way) road built before WWII, that has many curves and steep hills, with narrow lanes. The road was snow covered in the left lane, and just had 2 tire tracks in the right lane. I have the original tires with 45K miles. The car felt solid and maintained good traction the whole trip. I easily past most vehicles I came upon. Definitely one of the best vehicles I have driven in snow.
    As far as your specific problems are concerned, I would not go to the dealer, but find a good independent alignment shop in your area. They should adjust both sides so they are symmetrical, not asymmetrical as you indicate, both front and back. It seems like your power assist is not working correctly, maybe you have a blown fuse? It is the 50A fuse #6 in the plastic box on the driver's side under the hood. Are you sure the car was never in an accident?
     
  20. Walt999

    Walt999 New Member

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    At this point I'm not sure of anything! Anyway, I visited the service manager this morning and communication with Toyota has been impossible as the corporation has been on vacation for all of last week.
    We have been trying to work out a date for service that is mutually agreeable to both of us. He now knows me by sight and I am sure that he is now convinced that there is truly a problem.
    He is working on establishing a time when the roving service consultant from Toyota corporation will be in Tucson to assess the problem because he is the one who can suggest and authorize replacement of parts such as the torque sensor assembly, ECUs and other major steering components.
    I would guess that this is one way for Toyota to monitor the dealer service personell, who because of lack of understanding and training, might otherwise unnecessarily swap out very expensive components.
    Again, time will tell -- but it's hard to be patient.
    Walt