Enhanced VSC

You cannot shut it off in the Prius.

 

VSC is Vehicle Stability Control, which tries to keep the car going in the right direction. You are thinking of Traction Control, which tries to keep the drive wheels from spinning. There is an "inspection mode" where traction control is disabled, but it is not intended for routine driving. You have to go through a set of magic incantations to invoke it. It can be used in emergencies, but it's not convenient or designed for everyday use.

Tom

 

cancel your order.

 

If you have good winter tires you don't need to shut off traction control to "power up" a hill. Pearl does -very well- in slippery conditions. You do have to be patient. If there is no traction you won't be going very fast, but a Prius will move. Now the early GII models did have a system that was a little too sensitive. The current GIII and models from 2006 are just fine.

And if you DID manage to shut off the traction control and spun the wheels for extended time there is a good chance you would cause mechanical damage! So don't!

 

There have been endless discussions on this. What follows is my (as usual) confused summary of these:

1. The 2010-on Priuses have a better VSC than the earlier model years. Apparently, it was common for the earlier model years to get randomly stuck in snow, unable to rock the car out of icy spots, etc. There are reports that if one stuffs a 2010-on model year into enough snow and ice, then, it too can get stuck - but it's harder to get the car stuck and easier to get unstuck.
2. There's a magic incantation procedure involving hitting the on button, window buttons, et. al. that can get the 2010-on Priuses into one of two non-VSC modes. It's complicated enough that it's unlikely that you'd be able to memorize it, so committing it to a piece of paper and stuffing the paper into a glove box will get you where you need to be. However, while I've seen the instructions, I haven't seen any posts of the flavor, "I turned off VSC and saved a call to a tow truck!". I'd be happy to be corrected.
3. I've personally taken the car out on a several acre parking lot with 3-4" of heavy, slippery snow and had fun trying to pull donuts and the like. My experience is that it's really, really difficult to get the car to do something strange, like getting stuck or flipping ends, since I was unable to do either, and it wasn't due to lack of trying. All reports I've seen plus personal experience have shown that the car is extremely stable on snow and ice, enough so that people haven't complained about the VSC, except for the inability to turn it off.
4. One can skizz the wheels in a 2010-on Prius, something that, from what I've heard, the early models couldn't do easily. I'm willing to be corrected on this one.

I do not know. I bought my car because I wanted something advanced and efficient. As a snow car, it's easily the match of my old '71 VW Beetle, and that thing could practically climb trees during the winter. Of course, the car's got low freeboard, so if you surf it on top of a foot of snow, you're not going anywhere anyway, but you'd only get out of that kind of trouble with a SUV or some other car with decent body clearance.

I've been through most of two winters with this car sans problems in New Jersey and, yeah, this year and the previous we've had decent snow. We've also had decent snow plows, too.

KBeck.

 

The better than reading of 100+ articles is to borrow the Prius from dealer and test it in your conditions. The VSC in prius is a best of all my cars, but the good winter tires are essential.

 

Once again, since this seems to be a source of constant confusion: Stability control is unrelated to a car's ability to go through snow or up slippery hills; that feature is Traction Control. Stability Control helps keep a car from rolling over by keeping it pointed down the road. Stability Control systems use rate gyros and steering angle input sensors to see if a car is responding properly to the driver's steering inputs. If a car fails to turn when requested, or starts to fishtail or spin, Stability Control modulates the power and applies individual brakes to bring the car back into control.

Traction Control, on the other hand, is all about maintaining traction with the drive wheels. On slippery road surfaces, Traction Control will modulate power to limit wheel spin. Better Traction Control systems will also brake a single spinning wheel, transferring power to the other drive wheel.

Stability Control = Keeping the car from spinning out and rolling over.

Traction Control = Keeping the drive wheels from spinning.

Let's try to use the proper terminology. When we use it the wrong way, it only serves to cause confusion and muddy these discussions.

Tom

 

Here's the video you need to see:

It sealed the deal for me. That plus the fact that I have driven through several snow storms this year here in New England with nary a problem.

Some or all of the Gen II Prii will not allow you to spin the wheels. The 2010/2011 Prii behave as you see in the video.

Personally I tested this on my 2010 on a snowcovered hill just after streets were plowed on a hill near my house from a dead stop. I just held the accelerator down half way and off I went. The traction control controlled the spin and the wheels did spin to get me moving.

So I guess the designers took the input and came up with a fix that allows wheel spinning without a switch to turn off traction control. I hope this helps.

 

Oops, I see that you took the leap of faith and were amply rewarded.

Welcome to the club. We welcome all your newbie posts as I am sure there will be several. However it is always best to type your concern in the google box at the top of the PC page. You'll be amazed at the detail in which even the most totally obscure issues have been discussed.

 

You have low expectations then. I didn't encounter problems with the TCS my first year due to the lack of snow, the Prius really pissed me off this winter with the amount of times the TCS had cut in and be extremely annoying.

 

I was taught as a teenager learning to drive to NOT spin your wheels on snow and ice because you'll lose control of the car and/or dig yourself a hole. Unfortunately, very few people south of Maine and Michigan seem to get this point. When I lived in CT, everyone floored the gas pedal when the first flake flew, and hence they all were off the road as I cruised by.

 

Exactly. Tire spinning will work for thin layers of snow and ice, where the spinning melts through to the road underneath. For most winter conditions, all spinning does is form a layer of lubricating water under the tires, reducing traction to nearly zero.

This is exactly how ice skates work. Unfortunately, what works well for gliding on skates does not work well for powering a car.

Tom

 

Well, I'm going to slightly disagree with you here.

Maximum static friction occurs an instant before the tires start slipping. So, if one is trying to get out of the "stuck" position, one puts the car in drive, gases it until the car surges slightly forward (at which point the wheels are turning but the car's not moving), then flipping the gearshift into reverse, the car surges backwards and the wheels start slipping in that direction. One then reverses and does it again, the idea being to get some kind of rocking motion started. And, once the rocking motion does get started, slipping around a bit, even quite a bit, on top of the snow, while the car is moving, is all to the good in terms of Getting Out Of There.

My understanding is that the traction control on the 2009 and previous Priuses was pretty aggressive and wouldn't let the wheels slip much, if at all, hence reducing the amount of surging back and forth one could do from the initial "stuck" configuration, never mind the "we're moving, but the car's all over the place" mode. In the 2010 and on Priuses the traction control allows for a bit more skizzing of the tires, enhancing one's chances of breaking free.

Don't get me wrong: I've seen the occasional idiot on an icy hill or just stuck at the gutter whose lead foot is all the way down, with the driven wheel(s) skizzing round and round and the car not going anywhere. It used to be a great way to burn up a differential. The worst thing about those idiots is that, once in a while, after fifteen minutes of trying, they'd break free anyway, somehow reinforcing the idea that they were doing it the right way!

KBeck

 

Your comment about static friction applies equally while the car is in motion, not just while it is stationary. Slipping around while the car is moving is not good in terms of Getting Out Of There. Slipping tires mean dynamic friction, which is less than static friction. Perhaps you are confusing this with swinging your wheels back and forth in order to get a fresh bite. The fresh bite idea is an effort to get away from the lubrication created by dynamic friction.

Just for full disclosure, maximum driving force occurs slightly after the tires start to slip. Classical physics tells us that static friction is always higher than dynamic friction, but classical physics ignores the plastic and adhesive qualities of many materials that are just beginning to melt. Traction control on diesel-electric locomotives maximizes motive force by allowing a carefully controlled amount of wheel spin. Any more spin would move the drive wheels fully into dynamic friction, and thereby reduce friction. Less would limit the motive force to that from static friction, which would be a bit less.

Unfortunately, this sort of traction control is difficult and expensive, limiting it's potential for use in automobiles. It doesn't apply to our example; I only mention it to keep one of the other engineers from jumping in and muddying the water.

Tom

 

Tom, I'm perfectly aware that a slipping wheel on a moving car is into the dynamic friction area. Seeing as you're from Northern Michigan, you know as well as I do that a full-scale skizz on the driving wheels is never a good idea. However, once a car is moving a bit (and that's what all the rocking is about, anyway) keeping it moving is what the name of the game is all about.

I remember leaving the corporate parking lot one evening and seeing some unknown-to-me coworker who had managed to dive-bomb his car clear off the access road, with the rear of the car ten feet from the road, all in about 8" of snow. As I drove slowly by, I could see him spinning his wheels to no avail. So, I parked a bit further up the road, walked back (he hadn't moved), and said, "Do you want to get out of here today?" He said, "yes", I told him to get out of the car. Some light-footed back and forth a few times to get the car rocking, then a full-bore rearwards momentum and skizzing around a bit had his car out of there. He told me he had been trying for fifteen minutes to do what I did in thirty seconds. Lightly on the gas!

KBeck

 

Agreed. Back when I used to drive a Jeep C-J5, I used a version of your slow-spin method. My Jeep, like all real Jeeps, had a two speed transfer case and a very low rear end. In low-low it was impossible for the wheels to spin at a high rate -- they just went around and around at modest speed. It was an excellent method for wading through really deep snow.

A friend of mine had a hand throttle on his Jeep. More than once I watched him use low-low and the hand throttle to push himself out of trouble. He would get the wheels turning at the proper speed, climb out, walk around back, and push. If he set the throttle a little high it made for an interesting foot race once his Jeep was free.

Tom

 

The fastest way to accelerate is to get max power to the wheel before the wheel starts to spin. While the Prius will let you do it up to a certain point, it will most likely cut you off. It's another story going up steep hills. The car can throw a fit and slam on the brakes when you need to maintain or gain momentum climbing sharp hills. Not fun.

 

Traction control on the Prius never slams on the brakes; in fact, it never applies the brakes at all. Perhaps you are confusing a reduction of power to slamming on the brakes?

Tom