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Can traction control be disabled?

Discussion in 'Gen 2 Prius Technical Discussion' started by BVR46, Mar 12, 2009.

  1. BVR46

    BVR46 New Member

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    I have an '06 Prius and would like to know if there is a way to disable the traction control without also disabling the stability control. My dealer service department says no.

    I would love to find the "right wire" and be able to switch it on and off or barring that possibility disable it completely.
     
  2. Boo

    Boo Boola Boola Member

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    No. As I understand it, if the Traction Control does not work you'll damage the Hybrid Synergy Drive.

    Why do you want to disable it?
     
  3. BVR46

    BVR46 New Member

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    I live in Montana and drive daily on ice and snow much of the year. I run studded snow tires on all my vehicles during the winter months and if it weren't for them, I doubt I could get the Prius up my driveway much of the time.

    This is especially exasperating because the Prius does a wonderful job at everything else. I have never had a problem driving a front or rear wheel drive vehicle with a manual or automatic transmission under the same conditions when I had complete control of it.

    When we have a temporary thaw and get slush over ice, or the thaw refreezes and we get fresh snow over ice, I have to take several runs at the driveway to get up it. If I can get rolling on the level area in front of the garage fast enough so that I can back off slightly on the gas pedal all the way up the driveway I can make it within a reasonable number of tries. Trying to hold the gas pedal down slightly (at a position that would result in a slow, steady speed on level ground) or trying to accellerate at all just results in the car's braking to a stop. It's embarrasing when a friend with a beat-up Dodge minivan can go right up my driveway and I can barely make it.

    Under these same conditions in town I have to wait until there is no traffic coming all the way to the horizon before I try to pull out on a street from a parking lot or I risk getting T-boned.

    I know how to drive on this stuff but the car won't let me do it. The traction control hasn't gotten me stuck or hit yet, but I expect it to, so I end up driving my four wheel drive pickup on many days when I'd rather drive the Prius.
     
  4. Boo

    Boo Boola Boola Member

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    One thing that I read once here, but have not been able to confirm (even though I've asked twice), is that if the Prius is in EV Mode, the traction control is not on.

    If this is the case, then I wonder if your problem (which many others face too, especially the owners of 2004 and 2005 Priuses which we suspect have an even worse traction control) could be solved if you were to install an EV switch, and use EV Mode for those short, occasional instances like going up a slippery driveway or other incline.
     
  5. BVR46

    BVR46 New Member

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    Since all-electric mode would be most practical for slow driving in-town it makes sense that stability control would not be needed and might be disabled. I'd like to have an EV switch for more reasons than just traction control. I've heard that they come on the Prius models sold in Europe but I always figured they would be a lot of trouble to install. Unless the installation is as simple as plugging a switch into the wiring harness I'm not sure I'd trust the local dealer to do it right.

    I will approach the dealer with that idea, sometimes the technical people there surprise me. This would certainly solve my problem.

    Another thought I had was to wait for the new 2010 Prius to come out and see if its traction control system cycles faster. If the system worked as fast as it should I don't think my problem would exist, I believe it would control the car as well as I could. If the new version is faster and is backward-compatible to my car I'd certainly consider updating its "control head", software or whatever if it wasn't ridiculously expensive.

    Heck, if the new model has more comfortable seats and more legroom to go along with a better traction control system I might consider just trading up!
     
  6. David Beale

    David Beale Senior Member

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    The dealer wouldn't install the EV switch. It voids the battery warranty.

    The 2010 has an EV switch. It -may- be better re traction control but I doubt it.

    The reason traction control is so sensitive is when the engine is stopped and you start off (from a light for example), it can take the engine 1/2 to 1 sec. to start. The rotation speed of MG1 is proportional to the vehicle speed and inversely proportional to the engine speed. Once the engine is running it's difficult to over-run MG1, but with the engine stopped and the powerful electric motor (MG2) spinning up the wheels it's easy to over-speed MG1. So Toyota "took steps" to protect the HSD.

    You -can- put the car in "inspection mode" which disables traction control, but it isn't intended to be driven in that mode, and destruction of the HSD (MG1 in particular) would be very easy. So not recommended.
     
  7. Boo

    Boo Boola Boola Member

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    Well the new model definitely has more comfortable seats, more adjustments (telescopic steering wheel, driver seat height adjustment and optional lumbar adjustment), more rearward travel in the driver seat, and more legroom.

    Don't know about the traction control other than what Toyota reps said -- that all of this (traction control, stability control, etc.) will work more smoothly together (whatever that means).

    I think a few people here have occasionally, temporarily disabled the traction control by tricking the car's computers (do a Search). But I understand that they risk damaging the Hybrid Synergy Drive if there's overspin or overspeed that an enabled traction control would otherwise prevent.

    After exchanging messages about the subject with qbee42, I have serious doubts about that one poster's contention that the traction control is off while the EV Mode is on. We wonder how that can be the case when the HSD drive configuration itself never changes when the car is in its different drive modes.
     
  8. jayman

    jayman Senior Member

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    The brakes have no involvement with the Prius "traction" control. My FJ Trac does indeed use the brakes, and it works very well

    For example, a ramp up to an open parking deck. Once side of the ramp is icy, the other side is bare, due to how the sun shines on it. My FJ with studless winter tires, will easily climb that ramp in 2H. My Prius with studded tires, will climb the ramp, but struggle a bit

    For what its worth, I'm no longer going to use studless winter tires on my FJ: they simply do not provide enough ice traction. I've preordered factory studded Nokian Hakkapeliitta 5 SUV winter tires for my FJ. On glare ice, my Prius will outbrake my FJ

    It's important to keep in mind that the Prius "traction" control is there to protect the hybrid system, not to enhance traction. I don't recommend putting the car into Inspection Mode - if you're not careful you could do a lot of damage
     
  9. ken1784

    ken1784 SuperMID designer

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    Following to jayman's comments...
    Please understand how the motor traction control works.
    TOYOTA: Company > Technology

    You lost tire traction because of no traction.
    To get more traction, you have to wear good snow tires or tire chains.

    Ken@Japan
     
  10. BVR46

    BVR46 New Member

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    I'm certainly not going to do anything that voids the battery warranty or that damages the electric part of the drivetrain so I guess I'll have to live with it.

    The car comes to a stop so fast when I try to accelerate I assumed the brakes had to be involved with traction control. My current and previous pickups were both Tundras with traction control and I got the impression they use the brakes as well.

    If the feature is not there to enhance traction it seems silly to call it "traction control". I'm probably not the only owner to misunderstand that.

    I have always used studded snow tires during Montana winters and wouldn't use anything else.

    Thanks to everyone for their posts. I studied this forum for almost two years before buying the Prius and I learn more every time I visit.
     
  11. jayman

    jayman Senior Member

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    I'm not sure what else you can do, as you already run studded tires

    The only obvious pattern to the Prius TC complaints has been with 2004-2006 model Prius cars. It appears only a handful have an issue. As VSC was optional for those years, maybe VSC programming has something to do with it

    [Sarcasm Mode = ON] Some 2004-2006 Prius owners claim their car will charge up a glare ice hill with bald summer tires [Sarcasm Mode = OFF]

    About a year ago, I test drove a new 2008 Prius. It's TC behavior was completely different than my 2004. That is, it pulsed the power so quickly that I could actually live with it, it never killed the power like my 2004 does
     
  12. donee

    donee New Member

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    Hi BVR...,

    Putting the car into inspection mode would probably not damage the motors or the battery if operated on slick surfaces. It may very well damage the mechanical parts of the transmission that link the two motors and engine together. This is also part of the HSD, buts its not the electrical part.

    The specific fear would be the shock load of the motor rotor momentum should the tires catch and decellerate rapidly on dry pavement, while the motors are all reved up to thousands of RPM. That shock load could damage the parts in whats called the Power Sharing Device, or the PSD. This is a bear can sized planetary gear set in the HSD transmission.
     
  13. BVR46

    BVR46 New Member

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    Thanks!

    Poor wording on my part, I don't want to damage anything beyond normal wear and tear.
     
  14. qbee42

    qbee42 My other car is a boat

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    There is also the potential for over-speed of MG1 if you get really carried away with spinning tires.

    Tom
     
  15. BVR46

    BVR46 New Member

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    I was a hotrodder and drag racer back in the '60s and I learned early on that quick acceleration and spinning your tires are opposites. On some surfaces a little wheel spin is necessary to get moving quickly, but the more you spin, the slower you accelerate. You quickly develop a feel for how much gas pedal you can give a particular car before you pass from acceleration into wheel spin and you learn to follow that point but stay just short of it.

    The balance is much more delicate on snow and ice and much less gas pedal travel is involved but that's sort of the principle I'd like to be able to use with the Prius without being short-circuited by the traction control feature.
     
  16. qbee42

    qbee42 My other car is a boat

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    What you are describing is called controlled slip. In general, static friction has a higher coefficient than dynamic friction, but there is a narrow zone between static and dynamic where maximum tractive force can be achieved. Modern railroad locomotives have traction control systems which optimize this automatically.

    I understand what you want to do, but the Prius traction control system is not designed for it. It's a limitation that you will have to live with if you want to drive a current Prius.

    Tom
     
  17. bwilson4web

    bwilson4web BMW i3 and Model 3

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    HIGHLY DANGEROUS!!!

    Since anti-lock brakes, traction control and electronic vehicle stability use the speed encoders from each wheel, in theory, one might disconnect the wires to the wheel speed sensors and disable all three systems. Of course disabling safety equipment has other effects dealing with warranty, insurance and violation of vehicle laws.

    One can imagine a number of interesting if highly dangerous configurations including a 4-channel, input microprocessor that generates 'spoof' signals for the various wheel inputs. Of course, this has the same problem of disconnecting them all.

    However, it is your vehicle and everyone's skin.

    HIGHLY DANGEROUS!!!

    Severe property damage and human safety may be put at risk.

    Like driving around without seat-belts, removing safety air bags, and gutting exhaust systems, there are something that qualify for the Darwin-Award. This is one of them.

    Bob Wilson
     
  18. qbee42

    qbee42 My other car is a boat

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    Bob, have you considered that your suggestion might be dangerous?

    Tom
     
  19. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Just "dangerous?"

    HIGHLY DANGEROUS!!!

    An interesting experiment best performed in an empty parking lot.

    Bob Wilson
     
  20. jayman

    jayman Senior Member

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    Hmmm, that sounds like a challenge ...