VSC Training, knowing what to expect

nyprius · 04-24-2006, 12:17 AM

I learned to drive 30 years ago in a V-8 station wagon with bald front tires in the snow. Over the years driving different cars, I've learned to handle a car well on snow and ice, for example, learning how to pump the brakes to avoid losing control and knowing how to turn into a skid to regain control.

Now, I'm in a car that doesn't perform as expected (05 Prius #6 with VSC). Through a computer program, the car decides when to remove braking from wheels, slow acceleration, etc. I don't recall seeing information in the owner's manual explaining specifically how the system works so drivers know what to expect. A couple of times I went into minor skids on slippery roads because the car was not responding as I wanted it to (ie: the wheels didn't brake when I wanted them to). One time I slid into a snow bank (fortunately with no damage). If I had full control of the brakes and acceleration, I could have avoided the slide.

The car attempts to think for the driver and interrupts what an experienced driver might ordinarily do. The driver can see the conditions, know what's ahead and respond with full information. The VSC computer can't. It makes simple mindless brake interruptions that may not always be in the best interests of safety.

Does anyone know where to find a detailed explaination of VSC and other Prius traction control features? It would be helpful to know what's going to happen when you step on the brakes or accellerate on a slippery road.

Also, is there a way to disable or modify the response of VSC and other traction features (ie: to customize it to the driver)?

VSC, ABS and other features make the Prius respond differently from cars without those features. For the safety of new owners that have driven more traditional cars, it should be clearly explained how the car will respond. I think it's a mistake to assume a new Prius with VSC will be safer in all situations.

**Tideland Prius** · 04-24-2006, 12:46 AM

I'm not sure which package you have but you're certain it has VSC? Cause try as I might, I couldn't get the darn thing to spin out on a snowy residential area.

VSC has a yaw sensor that determines if the car is spinning on its axis (i.e. if it's understeering or oversteering). If so, it will apply the brakes to individual wheels as needed to maintain control, something nobody can do since if we press on the brake pedal, all 4 wheels have their brakes applied. When VSC is engaged, the "Slip" indicator will flash and you will hear beeps.

Knowing what it does can help you since what you described up there, you may be countering what the computer was trying to do and by trying to outsmart the computer, you may slid into the snow bank.

I'm not sure what your previous car was but almost all new cars come with ABS so threshold braking may not always be the best way to stop. Just stop on the brake as hard as you can and remember to steer AROUND the object if you're not gonna make it and not just slam and hope to stop then blame ABS for not stopping you in time.

plasm · 04-24-2006, 12:53 AM

Hmm... well, you probably already know how ABS works, right? It pumps the brakes for you, so you don't have to. To take advantage of this feature, just step on the brake as hard as you can, and steer in the direction you want to go. No foot pumping allowed, and remember to steer.

The VSC system is designed to make the car go in the direction you're steering by comparing your steering wheel input to what the car is actually doing, then modifying the car's behavior to make it match your steering input. So just point the car in the direction you want it to go. The computer should figure out what to do so that the car keeps going in that direction. Don't turn into a skid, because if you do, the VSC will try to overrotate your car because that's what it thinks you're telling it to do.

It's kind of ironic that by making it easier for beginners to drive, it forces people who have learned how to cope with older technology to unlearn their skills. If you give us more information about what happened before, during, and after your skid into the snowbank, we could tell you more about what we think happened and how you should have reacted.

john1701a · 04-24-2006, 12:54 AM

<div class='quotetop'>QUOTE(nyprius @ Apr 23 2006, 11:17 PM) [snapback]244147[/snapback]</div>

Quote:

Does anyone know where to find a detailed explaination of VSC and other Prius traction control features? It would be helpful to know what's going to happen when you step on the brakes or accellerate on a slippery road.[/b]

You clearly misunderstand the purpose VSC. It only activates when you are taking a corner too hard and are not touching the brakes.

In other words, it is already too late for you to respond. Only a computer that has independent control of the wheels can at that point, since it has access to more than just a brake pedal offers and can react far quicker than a human.

Once per year is all the more I trigger the VSC. And it is pretty darn obvious that the assist was something I wouldn't have been able to provide.

As for your "brake or acceleration" comment, that's ABS & Traction-Control not VSC.

bsoft · 04-24-2006, 06:11 AM

<div class='quotetop'>QUOTE(nyprius @ Apr 23 2006, 10:17 PM) [snapback]244147[/snapback]</div>

Quote:

The car attempts to think for the driver and interrupts what an experienced driver might ordinarily do. The driver can see the conditions, know what's ahead and respond with full information. The VSC computer can't. It makes simple mindless brake interruptions that may not always be in the best interests of safety.
[/b]

This is a classic argument that has been used against systems like ABS and traction control in the past.

The simple fact is that VSC can react far more quickly than you can, and it also has the ability to brake individual wheels, which you cannot do either. When you activate VSC, you will know it. A light comes on and the vehicle beeps. If you have activated VSC, you are already driving beyond the limits of your tires, and you are already oversteering/understeering. If you drive at a safe speed for the conditions, and if you slow down to a reasonable speed when turning (particularly when road conditions are less than ideal), you should not be activating VSC.

The Prius is not a sports car, and it is not forgiving if you try to drive it like one. In the past 4 months, I have activated VSC once - and that was when I was taking a turn far faster than I should have. This is in Colorado - we have had some nice snowfall and really nasty icy conditions last winter.

Now, as for traction control, I think it's a bit overzealous - but it does do the job.

BoosPrius · 04-24-2006, 09:28 AM

<div class='quotetop'>QUOTE(bsoft @ Apr 24 2006, 05:11 AM) [snapback]244190[/snapback]</div>

Quote:

This is a classic argument that has been used against systems like ABS and traction control in the past.

The simple fact is that VSC can react far more quickly than you can, and it also has the ability to brake individual wheels, which you cannot do either. When you activate VSC, you will know it. A light comes on and the vehicle beeps. If you have activated VSC, you are already driving beyond the limits of your tires, and you are already oversteering/understeering. If you drive at a safe speed for the conditions, and if you slow down to a reasonable speed when turning (particularly when road conditions are less than ideal), you should not be activating VSC.

The Prius is not a sports car, and it is not forgiving if you try to drive it like one. In the past 4 months, I have activated VSC once - and that was when I was taking a turn far faster than I should have. This is in Colorado - we have had some nice snowfall and really nasty icy conditions last winter.

Now, as for traction control, I think it's a bit overzealous - but it does do the job.
[/b]

Is VSC needed in flat terrain, like in Louisiana? Our highest hill is Monkey Hill at the Audubon Zoo. A very scary 26 feet high, <g>.

Gary
2006 Prius

Gary

Brian K · 04-24-2006, 06:25 PM

<div class='quotetop'>QUOTE(BayouBulldog @ Apr 24 2006, 09:28 AM) [snapback]244211[/snapback]</div>

Quote:

Is VSC needed in flat terrain, like in Louisiana? Our highest hill is Monkey Hill at the Audubon Zoo. A very scary 26 feet high, <g>.

Gary
2006 Prius
Gary
[/b]

:-)

VSC doesn't care about altitude.

If you ever get an ice storm, first, stay home, 'cause you probably don't know how to drive on ice. But if you absolutely must go out to have someone crash into your vehicle the VSC will do it's best to insure your car is in control as it gets smashed. Odds are though that you won't go anywhere due to the Traction Control disabling the driving wheels since you won't know how to drive on ice and probably won't have tires for ice. Not picking on you, it's just that we see the videos of what happens when the extreme south gets any slick roads.

nyprius, it'd have been better if you had learned to brake on slick surfaces by feathering the brakes. ABS still works with feathered brakes and you are still in the "control" you desire. By feathering the brakes ABS is more of an assist than having the car take the braking over fully. I hate that also.

Do what I did, if you have a suitable place for it... I took the new fangled systems out in a completely empty parking lot after a spring snow storm and had at 'em. Tried some controlled braking, accelerating, and tight turns to see what to expect. Then I realized the car was faster than I was and then it'd hand control back to me, all done much faster than I ever could have reacted. On the trip home from that shake down test all of those systems came on multiple times. They're very good. It hepls to do this with summer tires on.

nyprius · 04-25-2006, 10:47 AM

Thanks very much to everyone that responded to my note!

I appreciate the helpful comments. It makes me feel better about VSC (I have an 05 prius #6 BC package with VSC). Two experiences caused me to post the note and feel the Prius handles poorly on slippery roads. First, I was driving on a plowed and sanded road that still had a little snow on it. Half way through a left turn, the car started sliding. I pumped the brakes a little (not completely releasing pressure). But the car continued to slide and went straight into a snow bank. My previous car, an 89 Camry, would have easily made that turn.

On another occasion, I was driving up a slight incline on a snow covered dirt road that had been recently plowed. Several other cars had just gone up the road. Half way up the hill, the tires started spinning a little, traction control slowed them down, the car stopped, then this is where the bad thing happened. The car started sliding backwards. Normally through a mixture of varying brake and gas pressure and steering, I would have been able to regain control of the car and at least back it down the hill. But my car started sliding like a stone. I seemed to have no control. It slid backwards, then sideways and got stuck in a snow bank.

I attribute part of the poor snow response to the close treads on the stock tires, and therefore will not go through another winter with them. However, I could tell the car was not responding as I wanted it to.

The car can brake wheels independently, which I cannot. But the car can't look down the road and make advanced determinations about what braking and accelleration are needed to safely make it through a given situation. The car must rely on instantaneous adjustments. These may be best in the moment, but they may also add up to the wrong overall move.

I did try the ABS, VSC and Traction control in a snowy parking lot. I could feel some of what it was doing. Nevertheless, I still have the feeling that I cannot predict how my car will handle in certain situations. And that makes me feel less safe, not more.

**Tideland Prius** · 04-25-2006, 11:50 AM

Well, you're right in that the stock tyres aren't great for heavy snow or in icy conditions. It probably snows where I live for a max of 2 days if I'm lucky before it melts or gets washed away by rain so all my snow time driving have been in empty lots doing stuff I'd never do on public streets hehe.

While the car cannot anticipate, that's where you come in. You see a curve and a snow patch and you can adjust before you approach the corner but what if there was a patch of black ice that you didn't see? That's when the car comes in. It's there "just in case" something happens that you didn't anticipate.

With regards to the slide and brake pumping, you need to re-learn how to not pump the brakes. You're the smarter one of the two so you have to have to work in conjunction with the car to get yourself out of the sticky situation. What you did was appropriate for a car without ABS and I have absolutely no doubt that you knew exactly what you were doing and you would've gotten yourself out of that situation but with the newer cars with stability control and ABS, don't pump the brakes. If you do, ABS won't engage since every time you lift, ABS disengages and won't engage again til it senses lockup and thus the crucial milliseconds lost by lifting up and reducing brake pressure increases braking distance (in most situations, not all).

DaveSheremata · 04-25-2006, 04:07 PM

<div class='quotetop'>QUOTE(nyprius @ Apr 25 2006, 09:47 AM) [snapback]244831[/snapback]</div>

Quote:

I did try the ABS, VSC and Traction control in a snowy parking lot. I could feel some of what it was doing. Nevertheless, I still have the feeling that I cannot predict how my car will handle in certain situations. And that makes me feel less safe, not more.
[/b]

Hey NYPrius - sounds like we're the same kind of driver - I really enjoy "surfing" a car in the snow - I grew up in Montreal. I used to have this rear wheel drive BMW 320i that was sooo fun to drive in the snow, even at speed on highways covered in snow. The camber of the front steering made sure that car was always going where you wanted and you could drive the tail in or out with the gas pedal - what a blast to drive.
For good and for bad, just about all modern cars have these optional safety features that take some of the joy of driving away... but generally do improve safety.
It sounds like you do encounter enough snow that you need snow tires! I've only had one fender bender ever, and it was a lot like your slide into the snowbank, but mine was turning a corner in downtown Montreal with cars all over the place! I was going REALLY slow too - there was just no way I would have held the road without snow tires. Up in Montreal "all season" tires are commonly refered to as "3 season tires" or sometimes even "banana peels"! I think I've heard a lot of New Englanders call them similar names. I'd bet that your reverse-downhill-auto-slalom would have been averted too!

Dave

Cheers!

04-24-2006, 12:46 AM	#2
Tideland Prius Super Moderator Join Date: Oct 2004 Location: Canada Posts: 13,932 My Car: 2005 Prius Package: B Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 11	I'm not sure which package you have but you're certain it has VSC? Cause try as I might, I couldn't get the darn thing to spin out on a snowy residential area. VSC has a yaw sensor that determines if the car is spinning on its axis (i.e. if it's understeering or oversteering). If so, it will apply the brakes to individual wheels as needed to maintain control, something nobody can do since if we press on the brake pedal, all 4 wheels have their brakes applied. When VSC is engaged, the "Slip" indicator will flash and you will hear beeps. Knowing what it does can help you since what you described up there, you may be countering what the computer was trying to do and by trying to outsmart the computer, you may slid into the snow bank. I'm not sure what your previous car was but almost all new cars come with ABS so threshold braking may not always be the best way to stop. Just stop on the brake as hard as you can and remember to steer AROUND the object if you're not gonna make it and not just slam and hope to stop then blame ABS for not stopping you in time. __________________ 2005 Tideland Pearl Premium Package as of 25th Oct 2004 VVT-i Emblem, Sport Pedals, OEM All-Weather Mats, Cargo Mat, EV Mod, JDM Prius Interior Footwell Lighting, DICE iPod Integration Kit, LED licence plate lights, Phillips Vision Plus 2008 smart fortwo passion coupé as of 28th Apr 2008 Foglights, dash pods, leather seats, OEM rubber mats, BRABUS alum. handbrake, LED licence plate lights & dome lamp

04-24-2006, 12:53 AM	#3
plasm Join Date: Nov 2005 Location: Cambridge, MA Posts: 56 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Hmm... well, you probably already know how ABS works, right? It pumps the brakes for you, so you don't have to. To take advantage of this feature, just step on the brake as hard as you can, and steer in the direction you want to go. No foot pumping allowed, and remember to steer. The VSC system is designed to make the car go in the direction you're steering by comparing your steering wheel input to what the car is actually doing, then modifying the car's behavior to make it match your steering input. So just point the car in the direction you want it to go. The computer should figure out what to do so that the car keeps going in that direction. Don't turn into a skid, because if you do, the VSC will try to overrotate your car because that's what it thinks you're telling it to do. It's kind of ironic that by making it easier for beginners to drive, it forces people who have learned how to cope with older technology to unlearn their skills. If you give us more information about what happened before, during, and after your skid into the snowbank, we could tell you more about what we think happened and how you should have reacted. __________________ 2005 Salsa Red Package #4 - "Mooberry"

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04-24-2006, 12:17 AM	#1
nyprius Senior Member Join Date: Oct 2005 Location: Saratoga Springs, NY Posts: 340 My Car: 2005 Prius Package: #6 Nominated 2 Times in 1 Post TOTM Awards: 0 Friends: 0	I learned to drive 30 years ago in a V-8 station wagon with bald front tires in the snow. Over the years driving different cars, I've learned to handle a car well on snow and ice, for example, learning how to pump the brakes to avoid losing control and knowing how to turn into a skid to regain control. Now, I'm in a car that doesn't perform as expected (05 Prius #6 with VSC). Through a computer program, the car decides when to remove braking from wheels, slow acceleration, etc. I don't recall seeing information in the owner's manual explaining specifically how the system works so drivers know what to expect. A couple of times I went into minor skids on slippery roads because the car was not responding as I wanted it to (ie: the wheels didn't brake when I wanted them to). One time I slid into a snow bank (fortunately with no damage). If I had full control of the brakes and acceleration, I could have avoided the slide. The car attempts to think for the driver and interrupts what an experienced driver might ordinarily do. The driver can see the conditions, know what's ahead and respond with full information. The VSC computer can't. It makes simple mindless brake interruptions that may not always be in the best interests of safety. Does anyone know where to find a detailed explaination of VSC and other Prius traction control features? It would be helpful to know what's going to happen when you step on the brakes or accellerate on a slippery road. Also, is there a way to disable or modify the response of VSC and other traction features (ie: to customize it to the driver)? VSC, ABS and other features make the Prius respond differently from cars without those features. For the safety of new owners that have driven more traditional cars, it should be clearly explained how the car will respond. I think it's a mistake to assume a new Prius with VSC will be safer in all situations.

04-25-2006, 10:47 AM	#8
nyprius Senior Member Join Date: Oct 2005 Location: Saratoga Springs, NY Posts: 340 My Car: 2005 Prius Package: #6 Nominated 2 Times in 1 Post TOTM Awards: 0 Friends: 0	Thanks very much to everyone that responded to my note! I appreciate the helpful comments. It makes me feel better about VSC (I have an 05 prius #6 BC package with VSC). Two experiences caused me to post the note and feel the Prius handles poorly on slippery roads. First, I was driving on a plowed and sanded road that still had a little snow on it. Half way through a left turn, the car started sliding. I pumped the brakes a little (not completely releasing pressure). But the car continued to slide and went straight into a snow bank. My previous car, an 89 Camry, would have easily made that turn. On another occasion, I was driving up a slight incline on a snow covered dirt road that had been recently plowed. Several other cars had just gone up the road. Half way up the hill, the tires started spinning a little, traction control slowed them down, the car stopped, then this is where the bad thing happened. The car started sliding backwards. Normally through a mixture of varying brake and gas pressure and steering, I would have been able to regain control of the car and at least back it down the hill. But my car started sliding like a stone. I seemed to have no control. It slid backwards, then sideways and got stuck in a snow bank. I attribute part of the poor snow response to the close treads on the stock tires, and therefore will not go through another winter with them. However, I could tell the car was not responding as I wanted it to. The car can brake wheels independently, which I cannot. But the car can't look down the road and make advanced determinations about what braking and accelleration are needed to safely make it through a given situation. The car must rely on instantaneous adjustments. These may be best in the moment, but they may also add up to the wrong overall move. I did try the ABS, VSC and Traction control in a snowy parking lot. I could feel some of what it was doing. Nevertheless, I still have the feeling that I cannot predict how my car will handle in certain situations. And that makes me feel less safe, not more.

04-25-2006, 11:50 AM	#9
Tideland Prius Super Moderator Join Date: Oct 2004 Location: Canada Posts: 13,932 My Car: 2005 Prius Package: B Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 11	Well, you're right in that the stock tyres aren't great for heavy snow or in icy conditions. It probably snows where I live for a max of 2 days if I'm lucky before it melts or gets washed away by rain so all my snow time driving have been in empty lots doing stuff I'd never do on public streets hehe. While the car cannot anticipate, that's where you come in. You see a curve and a snow patch and you can adjust before you approach the corner but what if there was a patch of black ice that you didn't see? That's when the car comes in. It's there "just in case" something happens that you didn't anticipate. With regards to the slide and brake pumping, you need to re-learn how to not pump the brakes. You're the smarter one of the two so you have to have to work in conjunction with the car to get yourself out of the sticky situation. What you did was appropriate for a car without ABS and I have absolutely no doubt that you knew exactly what you were doing and you would've gotten yourself out of that situation but with the newer cars with stability control and ABS, don't pump the brakes. If you do, ABS won't engage since every time you lift, ABS disengages and won't engage again til it senses lockup and thus the crucial milliseconds lost by lifting up and reducing brake pressure increases braking distance (in most situations, not all).