Traction Control

This deserves a sticky or something. It could save somebody a lot of grief.

I wonder if it will work in snow, ice, or gravelly hills.

 

I have never have any problems with traction in Ice, snow, or gravel with my 2005 so I can't really say if it would pass the test.

The three big problems that we have in my area are rain, rain, and did I mention rain?

No, the reality is that black ice and sheet ice are the two biggest dangers that we see. (Other than the loose nut behind the other wheel.)

Black ice is what we have this morning. It was 28 degrees when I went up to the store this morning. We had two dry days so the roads aren't covered with ice. We have tons of fog and areas which never dried completely so we have lots of black ice.

I keep my speed down and never 'feel' the icey spots because of the traction control/VSC combo. I know that the ice is there because everyone and their brother decided to go out this morning.

Two cars were in the ditch at our corner. One had run into the first. Five more on the way down the hill.... I saw the patches where they ran into trouble but I never felt it.....

I should mention that I also have new tires which were highly rated for ice and snow, but the car had the same feel with the old tires.

I do have one route that I use on an irregular basis which involves a 3 mile drive on a gravel/dirt/dust/what_the_heck_is_that road. by using common sense and a light touch on the throttle I have never gotten bogged down.

I did get a wonderful rush one year when I passed a Yukon on the way out from camp. They got stuck where I had driven two hours earlier. But the key there was not the basic ability of the vehicle. It was that common sense thingy....

Four wheel drive does not confer invulnerability to the laws of physics. But many up here do not understand that..... (If your tires are bouncing four wheel drive cannot work.)

 

I understand your pain, but we all forget from time to time. To explain PriusEnvy's point:

Traction control exists on every Prius. That is the (relatively basic) system used to prevent over revving and is (as I understand it) a basic part of the Hybrid synergy system that Toyota uses.

VSC is the system that exists in some packages which kicks on when the temperature is below 38 degrees. It kicks back off when the temperature is above 39 degrees. (This knocks 2 to four miles per gallon off of my mileage.)

I wish that we actually had a method to control VSC by a button so that we could turn it on in other than Icey conditions......

Anyone know of a secret handshake for that? other than the dry ice block taped to the thermometer?


Hey I can go out and test my tires in the snow! We have large flakes coming down! A Crisis in Clark County!

 

vsc

vsc isnt just for cold environments, its always there and ready for you when the time calls for it example, driving 50 mph and a sudden rapid steering movement takes place, VSC will kick in.

motor TRAC is used when wheels begin to slip, the system automatically reduces engine power to keep those wheels from losing traction.

both the traction control system and the ABS system are very sensitive for some odd reason on the toyota prius, personally, driving on snow or ice i think its dangerous to have this sensitive system, once i almost ran into a police officer in Newark, because ABS kept kicking in and the vehicle wouldnt slow down ( i had to push handbrake )

 

I'm still puzzled why Toyota couldn't make the Prius Trac work like it does on my FJ Cruiser. That system works as intended and is quite helpful

With our recent snowfall, on purpose I slowly drove the right side of my FJ into a mound of snow pushed up by a snowplow. I kept going until the FJ bogged down, and I thought I would need to shift into 4H

I put it in R and gave it some gas. The wheel on freshly plowed road dug in and with a bit of rocking I was able to get out. The system allows minor wheelspin

Tires make a huge difference too. I'm running studded Goodyear Nordic tires on the Prius and Toyo Open Country G-02 Plus studless winter tires on the FJ

 

i have a 06 tacoma with TRD package, i think its the same 4.0 v6 ( 1GR-FE ) as your FJ cruiser .i dont have trac, or vsc, last winter i was pulling in my driveway, and got stuck where the dip is ( full of ice ) im pretty sure if i had traction control i would have been able to get in, i usually just let it spin until the ice gets hot.

honestly i think toyota should have put this sensitive traction control system on more powerful cars, like the new camry V6, and tacoma/fj/4runner, most of them have TRAC function but its not as sensitive as the toyota prius.

I think on the GS450h you can actually turn off motor TRAC

 

A properly engineered Trac system, absolutely yes. One that is too sensitive, nope, you're stuck even sooner. I've managed to come to a stop halfway up a steep gravel hill that other cars can make with minor wheelspin

The way the Trac works on my FJ, the brake is applied to the spinning wheel, so there is actual torque transfer. It allows minor wheelspin so you won't grind to a stop. The Prius Trac only reduces torque, it doesn't apply the brake to the spinning wheel and there is no torque transfer

This weekend at the hobby farm, I did purposely drive very slowly into a snowbank until I got stuck. Sort of like the experiment I did last weekend on the city street. The Trac allows minor wheelspin even when bogged down.

So I shifted into 4H and easily backed out. If I had tried that in the Prius, the car would have remained motionless even with the gas pedal right to the floor.

My Prius appears to have the hyper-sensitive Trac, in that it refuses to allow even minor wheelspin. Instead, the wheels just stop turning if the car is bogged down. On glare ice, the turn/stop cycle is around 2-3 secs.

With studded tires, minor wheelspin is helpful to launch you on glare ice, as the studs dig into the ice. At least with my current studded tires - Goodyear Nordic from Canadian Tire - I finally have a good winter driver. This tire is exactly the same as the Goodyear Ultra Grip 500 sold in the EU

http://eu.goodyear.com/home_en/tires/repository/UltraGrip500/index.jsp?page=benefits

If you click on "Profile" you get a Flash presentation about the tire. It ranks very highly in EU testing, very slightly behind the Nokian Hakkapeliitta 5. Here in Canada, around $122 a tire studded, mounted, and balanced

However, the tread design of the Goodyear Nordic makes for a noisy ride on dry roads. Given how severe and long the winters are up here, that's a good compromise

 

Lowering the tire pressure on sand is a well known technique to allow the vehicle to "float" on the sand. If you stand on the throttle you will still sink, so driver skill is still the best "equipment" to have.

DO NOT lower the tire pressure on snow or ice! Most tire manufacturers recommend RAISING the tire pressure slightly! The tire clears the snow out of the tread better with higher pressure, and you want the tire to "sit in" the snow, not float on it, so you get the traction available from the sidewall and edge of the tread in the snow.

If you are having trouble getting enough traction to move, a slight wobbling of the steering will do wonders. This enhances the sidewall traction. Works best on FWD and 4WD vehicles (doesn't do much on RWD). If you want to use this in a AWD vehicle, first lock it in 4WD (unless it's a FWD normally system). This technique is really effective in mud. Gentle throttle to get the wheels spinning slowly, then rock the steering back and forth. The vehicle will start to slowly crawl ahead. This would probably not work with the Prius, but try it and see, if you -do- get stuck.

Why is the Prius Traction control so aggressive?
Think of MG1 RPM. It's proportional to the spin rate of the wheel and inversely proportional to the RPM of the ICE.
When you are on a low traction surface, the wheel spin rate can increase rapidly, due to the high torque of MG2. The increase in spin rate is higher than the increase in spin rate the engine can achieve, especially if it is shut down. So to avoid over-spinning MG1 Toyota's engineers had to tightly control wheel spin-up.

This isn't a concern in any other non-HSD vehicle.

Perhaps the next generation HSD will include a low traction wheel RPM control system where the throttle controls wheel RPM, not power. Maybe even with a switch to engage it for use on a 4WD vehicle (hint hint Toyota). That would give you a very capable off-road vehicle.

 

The secret handshake is any lateral panic maneuver. You'll hear three fast, successive beeps letting you know the VSC is concerned with what you're doing.

~ dan ~

 

I wonder if a torsen differential will fit in the Prius? I know they are available for Corolla and other vehicles in the Toyota lineup.

These are the cleverest differential ever invented. What ever torque is delivered to the wheel with the least traction in a wheel spin situation, up to 4 times that torque is available at the other wheel. In other words the most torque goes to the slowest turning wheel. http://en.wikipedia.org/wiki/Torsen

 

Very interesting. That could solve a lot of the traction issues a Prius has, but I wonder if it would in any way confuse the Trac system? With my other vehicle - a 2007 Toyota FJ Cruiser - the various electronic and mechanical traction aids all work together quite nicely

http://www.toyota.ca/cgi-bin/WebObj...ruiser-FANkARlqc5TNhtUIPzfDtg/3.15?index.html

My FJ Cruiser has Trac, VSC, A-TRAC, and a locking rear axle. Shifting the transfer case into 4L, and pushing the A-TRAC button, each wheel is monitored for wheelspin. If a wheel is in the air - say travelling across a deep rut or ditch - the brake is applied to that wheel.

If things get really dicey, push the Diff Lock button and a shift actuator in the rear axle forces a splined collar into the case, locking both rear axle shafts together. This all works with the electronic traction aids too.

Since I can readily drive and compare the various Trac and VSC algorithms in my 2004 Prius and 2007 FJ, I really have to wonder why Toyota couldn't have implemented the same Trac in the Prius: front wheel spins, apply brake to that wheel.

For reliable and brute force traction, I'm sold on PowerTrax LockRight mechanical locking rear ends. I have a 1984 Ford pickup as a work/plow truck at my hobby farm, and several years ago put the LockRight components into the Ford 8.8 rear end.

Took about an hour, very easy, and reliable. The rear axle is always locked until you try a sharp turn, then the outside wheel overruns and you hear a "clickclickclick" noise.

http://www.powertrax.com/lockright.html

 

I remember reading about something in the owners manual about what to do if you get stuck... don't remember what it said to do but I think it had some sort of method you could use to get out (and I don't think it involved accessing any of the service modes...). If all else fails, you have the tow hook you can attach to the front bumper and have someone pull you out. Or, if you're not in a rush to escape a rising tide, you could probably use a ratcheting strap to pull your own car out, assuming it's long enough and you just happen to keep one in the car and have something nearby to tie onto.

-That might be a good mod, add a winch that runs off the traction pack... LOL...

 

Well, add me to the list of people who have have troubles with TC/ABS. I find the TC and ABS in my '06 to be far more aggressive than I've ever experienced in other cars. Quite frequently I find that if pop out of a gas station (right turn out, usually a bit of slop down to street level, and many times a pot hole develops there), as I make the turn, and am accelerating out, I lose almost all acceleration for a second or two.

Also, if I'm braking rather easily, and happen to go over a pothole, frequently I can feel the brakes release very noticeably. I've never experienced anything like it with ABS on other vehicles, except with snow/ice. It actually scares you into thinking you're going to hit a car that's braking in front of, for example, when you're slowing down at an intersection. This is the opposite of what ABS is supposed to do! These potholes absolutely would not be a problem without ABS, or with any other ABS vehicle I've driven.

I certainly consider it defective. I do still have the OEM tires, but that's really no excuse for this kind of performance.

As for snow performance, generally -- I have actually found it to be quite good, most of the time, despite the fact I have just OEM tires -- which I have mentally attributed ot the overly aggressive TC. The only trouble I have is with steep hills. I have a steep driveway, without much ability to get a running start, and I invariably have trouble with it.

 

I don't think it is fair to consider it defective - it is obviously safe, reliable and non-random.

But it is way too sensitive and too actively engaged in changing the output of your car compared to what you're asking of it.

I also feel worried in the acceleration stutter; am I going to make that kinda close turn? That guy looks like he's approaching a lot faster and closer than I thought.

~ dan ~

 

The Prius differs from other cars in two major ways: 1) It has incredible torque at zero rpm, and 2) Most braking is regenerative through only the front wheels. The traction control has to be aggressive to keep drivers from destroying the HSD. It could be a bit better, but there is a reason it's so sensitive. The loss of braking you feel going over a bump is from the front wheels loosing traction. When this happens, the Prius can no longer use regenerative braking, so it switches to friction brakes. The brakes work fine, but you can feel the transition from one braking system the the other. It's not defective.

Tom

 

I fear I have to disagree. I can't consider this to be either safe or reliable. It's not like this is something that happens every time you brake. It's dependent upon conditions, and is a relatively rare event -- so it's not predictable. It may not be random, because we know the circumstances under which it happens, but since those circumstances aren't predictable for a driver, it might as well be random. It's not like you know its going to happen, so you naturally adjust the way you break. Therefore, it's not reliable.

And I certainly can't consider it safe. If I feel the brakes release and get a serious scare that I'm going to hit the guy in front of me who's also braking -- that's not safe. It's not like I'm not somebody who tailgates the guy in front of me, so I have no margin of safety -- but if something were to cause the car in front to panic stop right as that were happening, god help you.

(On the TC side, it's a bit different. That happens a bit more often, and in more predictable situations, and therefore, one can more easily adjust for such. So that falls closer into the realm of a behavior that I just don't like....)

I'm an engineer also, and that sounds like a plausible explanation of what's happening, but it's just that -- an explanation of what's happening, not a justification of the end result.

If that's how it behaves, then they need to go back to the drawing board and figure out how to make it behave better -- i.e., how to effect a smoother transition to conventional friction brakes, so that braking power doesn't drastically change as the transition is effected. A second or even 1/2 second of drastically reduced braking is an eternity in terms of distance....

Also, frankly I'm skeptical that a tire -- let alone both tires -- are actually losing sufficient traction for it to be a problem. (If it were, then I'd expect to have encountered similar experiences with potholes on other cars, both with and without ABS. I never have.)

Rather, I would suspect that what's happening is that there's a differential between the rotation of the two tires, because one is travelling vertically, in addition to forward -- and that the algorithm being used by the ABS (and TC) computer to evaluate traction status mistakenly decides that traction has been lost, requiring intervention.

If so, they need to figure out a way to adjust the algorithm, for this is certainly a normal situation, much like a turning differential is a normal situation (albeit their characteristics are very different).

Bottom line, in my view -- the fact that it's not easy for them to solve the special problems they have for hybrid system with regenerative braking doesn't justify a poor result, or make it acceptable.

 

Yesterday, I was in Peterborough, Ontario where heavy showers of ice pellets were forming a slushy layer over pre-existing ice. I was leaving a family gathering with several others and had to exit up a very steep hill. Three GMs and a Ford (two were SUVs) took over five minutes to climb the 200 yd length of the hill, with some literally sliding curb to curb on the way up. The slip light on my 2008 Prius flashed once as I covered the same stretch in about 15 or 20 seconds from a standing start on the hill. I chalk it up to good snow tires and gentle application of power.

We've had pretty slippery roads here this year. I've had no traction problems at all with this car. It handles my steep driveway better than my prior two (very sure-footed) Volvos and my Sienna.

Has any else changed tires and found the traction issues solved?

Cheers,

Geoff

 

As I've mentioned before, when I readily compare my 04 Prius to my 07 FJ, it does tend to make the Prius quirks all the more obvious. Something as primative looking as my FJ can easily be driven in 2H on ice and deep snow, with no issues.

Yes, I have very good winter tires on my FJ, though not studded. I did finally get my FJ stuck at my hobby farm, I purposely drove into a snow drift until it bogged right down. Had to shift into 4L, engage the rear locker, and spend 5 mins gently rocking back and forth until it managed to free itself. Snow was up to the running boards

My Prius is ok on most surfaces thanks to the aggressive studded winter tires I run. However, as I found out last winter at the hobby farm, once it does bog down, the wheels refuse to turn. Therefore I can't rock it, and need help with a push or a pull using the tow eyelet

 

Hard to believe you're having a *much* worse winter than we are! Especially the snow and ice, though we had freezing drizzle last night

Next time at Canadian Tire, check out their Goodyear Nordic winter tires. I have those on my car, and they are also studded. This is a very aggressive winter tire, noisy on dry pavement. However, on icy roads and snow under 3 inches, they work great. The ice traction is much better than the studless Toyo Open Country G-02 Plus I run on my FJ Cruiser

This is the same tire as the Goodyear Ultra Grip 500 sold in Europe. The following site has a nice Flash presentation about the tire, click on "Profile"

http://eu.goodyear.com/home_en/tires/repository/UltraGrip500/index.jsp?page=benefits

The tire is very reasonably priced, around $124 a tire with studding

 

Jayman, I think you may have mis-read my post. I'm running on good winter tires (Nokian Wrs) and I don't have any traction problems at all.

Cheers,

Geoff