Traction Control --- It worked... I Think.

If you try this when you're turning you trip VSC as well as Traction control. In that case you also get a "beep". Same light is lit I think (usually when I trip VSC I'm not looking at the light as it's very slippery and I'm concentrating on the road!!). I will admit however that I have watched the TRAC light flicker a few times, just wondering how many times it will try before giving up. It seems it never does give up, at least so far. 15-20 trips of the light in a row (very slippery snow/slush, and I was trying to keep out of the way of the 18 wheelers - however it seems that is an unnecessary panic, as the Prius seems to have better traction or control than most other cars I've encountered in these situations).

It does help a lot that Pearl is wearing Nokian WR tires.

 

I have been in Toledo most of the week and encountered a pretty good snow storm on Tuesday. It was the first extensive winter storm encountered. Here are my observations on the traction control. I never experienced how it worked before this.

Overall the traction control works great with some problems encountered with starting out from complete stop. The conditions were flat roads with no hills. Street condition: 1) Snow covered unplowed streets up to 4 inches. 2) Plowed streets with snow cover. 3) Slush/melting snow due to salt. Outside temperature 20-25 F. Cloudy.

Driving with momentum: In this driving condition, the Prius is awesome. As described in previous posts, once the Prius gets up to 5 MPH the traction control works wonderfully. You have complete control of the vehicle. You can floor the "Go pedal" and the tires will not spin out of control. The traction control will stop the tires from spinning and almost always it engages in the VSC. The Prius is very stable.

Driving from a stop: Here is where the Pruis operates differently then previous vehicles I have driven. From a stop, the Prius engages the traction control almost instantly. What is a different experience for me, is the way it operates. Essentially it stops the wheels from breaking traction by reducing the power supplied to the wheels all the way to no power if needed. This can be very disconcerting if you are not ready for it. It can be dangerous if you are relying on the power. I think it is a mindset thing. I used to think that the "Go pedal" was a direct connection to the engine. In the Prius, the 'Go-pedal" is a power "request" from the ECU. If you are expecting the tires to spin to start your movement, it is not going to happen that way in the Prius.

From a start, the wheels start to spin, the tires almost always break traction and power is reduced. My reaction is to further depress the "Go-pedal". I expect that the engine and power should increase and the wheels should spin. The exact opposite happens. Power is decreased and the wheels stop spinning. They intermittently spin in an attempt to start momentum and continued forward movement. If the conditions are very slick, the Prius will not be able to gain enough traction to move and the car feels like it has shut down. I can push the pedal all the way to the floor with no reaction. At first this is disconcerting and then annoying. What I expect the car to do is add power in an attempt to "power" out of the condition. When the car cuts power, I initially thought it was not working, but it actually works very well.

I was never stuck in the Prius. Several times I was able to encounter a condition that the Prius would not go forward. With the “Go-pedal†completely depressed, the Prius just sat there, intermittently spinning a tire then stopping. The fix was to back up a few feet until stopped in the rear by the traction control and then go forward. This is equivalent to rocking in the old days. After a few times, the Prius was able go forward.

My feeling was that if I couldn't go forward in the Prius, I wouldn't have been able to go forward in my old vehicle. The one difference that I noted is that the Prius doesn't dig holes that my previous vehicle did. I used to gun the engine and the tires would spin and dig them selves in deeper. Then is was harder to "rock" out by using reverse.

Summary: The traction control works great. From a stop it operates differently from my previous experience so plan for the new operating environment.

Recommendation: Use extra caution when turning in front of oncoming traffic.

 

Hey, that's one of the better explanations of what to expect
from the TC that I've seen -- reasoned observations, none of
the whining that usually crosses the boards. You touched on one
important concept that I realize I've gotten very used to under
most driving conditions and any weather, and is one of the
primary tools for hypermiling: apply a gentle bias to a control,
and *wait* for the results. That goes for acceleration, steering,
and braking, and of course requires good ability to predict
where you want the car to be in the next 10 or more seconds.
Many people drive as though they wanted the total effect of their
control movement to complete instantly -- like screaming up to
the next light and cramming on the brakes, they wanted an
instant go and an instant stop. I, and anyone driving for
MPG, will rather look at the distance, the timing of where the
next light might be in its cycle, the surrounding traffic ...
and try to apply just enough of a pulse to carry me there.
When beginning to move at very low-speed situations, such as
parking lots, I'll usually apply a tiny bit of go-pedal and
then just let the car drift along -- no abrupt changes in speed
or even the power request itself. This makes everything very
smooth and predictable.
.
Which is exactly how you want to be driving on an, um,
frictionless surface.
.
_H*

 

Where I come from I was taught on a slippery surface use light throttle. Not snow or ice but slippery wet clay. I guess this is true for the Prius too.

 

I'm glad you got home okay, despite the ordeal.

We similar problems on Tuesday night down here in the DC metro area. Traffic was stopped in 395 South coming out of DC and also at the mixing bowl (confluence of 395, 95 and 495) due to ice on overpasses. As a result everyone bailed onto the surface roads that happen to be all around my neighborhood. Luckily a co-worker alerted me to the traffic jam so I stayed at work until the worst was over. I was lucky that I only encountered one slippery stretch of road although I too found the sidewalks to be a sheet of ice.

 

Hi Bestmap...,

I have to agree with Hobbit, that is one of the best, if not the best summaries on the operational aspects of the Prius traction control.

I think there is a real difference between the Prius and other cars, as has been noted, but there is also an exageration of the difference too. If your on warm ice on the 2 drive wheels, no car is going to go. Many winter driving comments are based on people getting stuck in a situation that other cars would have the same problem - in my opinion.

Here is what I think the difference is. It has to do with the very high torque of the Prius MG2, and the discrete time nature of the controls. What happens is if an out-of-control condition starts, then there is a small time it takes the control to detect the level of out-of-control. The longer that time, the more out-of-control, or high difference between slipping wheel and the running wheels. The higher the difference, the greater the reduction in power. The longer the sampling period the control has, the more out-of-control things can reach, and the more the power reduction will be applied. If there is any fault in the Prius, its that the computers are not crisp in their speed of action, and this coupled with the really large creeping speed torques available is the issue. The higher the torque, the higher the slip can get between samples.

So, if one attempts to accellerate normally and hits a slick spot unexpectedly, rather than catching the slippage as it first happens, the slippage is going at a good rate before the computer kick in the traction control, and that makes the level of action that much greater. This might also have to do with the change over from electric to hydraulic control of the brakes. This may cause an extra delay.

The best advice to new Prius icey road drivers is use very little pedal from the start. This avoids slipping in some cases, but also, it avoids the magnitude of slippage that can occur between control system samples. And thus limits the impact of the correction the system takes.

 

Thank you for the nice comment. I agree with you about the slow system. The hardest thing for most people to get used to is that your foot is not in direct control of the engine. so when you floor it on ice or snow it is not going to just turn the wheels and dig a hole. In the Prius you can't just "power" your way out of it.

After diriving the Prius in the snow, I think it is one of the best 2WD cars I have driven in ice and snow. Will it get stuck, yes. So would my other cars.

 

Just got a 2008 Prius and put new Hankook H727 Optimo tires on, based on good Consumer Reports rating for snow, ice, dry and wet. The weather cooperated with my scientific curiosity by applying a thin layer of ice to my long steep driveway, and I did not treat the driveway in anyway with melter or sand. The Prius with the Optimos handled it beautifully. I did not find the traction control to be very assertive, and really would have wished for more, not less, "intrusiveness" (which I prefer to call "help") from it. Most interesting were my experiments with stopping and restarting on the slick, steep hill. If I gave it a lot of "go" pedal (which I call "driving like a jerk on ice") the wheels would spin and the car would slide backwards down the hill. If I gave it very little go pedal, and even less go pedal any time it started to slip, it would crawl right up the icey incline at 1 or 2 mph. I doubt any 2-wheel-drive vehicle without traction control would have been able to get up the hill starting from dead stopped. It really was quite impressive. Conclusion: (1) Judging from other comments, my traction control is less (sensitive, intrusive, assertive, heavy-handed, helpful -- choose your adjective) than other Prius owners have -- maybe because it's a later model. And (2) going up an icey hill is a case where less go pedal means more forward motion. Also (3) count me as one Prius owner who would welcome more (insert adjective) traction control. But what I have is fine. My wife did fine with it too, under the same conditions.

 

Tires! That's the first reason you did well.

Intelligence! That's the second reason you did well. You DON'T mash the accelerator pedal when it's slippery!

I suspect there is no difference in the traction control between your car and any 2006 to 2009 Prius. There IS a big difference in drivers and tires!

 

I went to hike the grand canyon two weekends ago and its the first time I've got the Prius stuck. I have 4x4 vehicles that I would usually drive (I live in San Diego), but its 550 miles to the canyon one way and it was a one day sort of trip, so 45 vs 12mpg was favoring the Prius. We tried to camp off a forest road near the south rim entrance but the prius sucked in the snow, no other words for it. The air dam plowed the snow, lots of scraping noises underneath and when I stopped, I couldnt get started again. I am certain that with any other FWD car w/o traction control, I would not have been stuck. The tires would not turn, it would send no power to the front tires. I had friends that pushed me out, but it bothered me that it would have been hard to put chains on at that point (I had them with me but it was 2am and I wanted to camp). I wish the car had a traction control/safety nanny "off" switch, sort of like my wife's mini cooper S. For 99% of the time, I'd leave it on.

 

Snow tires are the best form of winter traction control.

I accelerate much like I do in the summer, on solid ice, in the winter here in MN and don't have any problems. Only rarerly does traction control kick in.

Best,

Jonathan

 

After reading these posts, I have to wonder - has anyone made the Prius drift, as in the movie, "Fast and Furious - Tokyo Drift"?

Sorry, someone gave me the movie for Xmas, and I have to wonder about this driving technique.....

 

It is pretty difficult to drift FWD vehicles, but it can be done. I have not tried it on the prius, but on the ice, you can easily get lift off oversteer if you are aggressively cornering. If you take it a step further, namely, enter the corner, create an understeer condition, and then lift off to correct, you will end up in a 4 wheel drift.

realistically, you would have to turn off traction control to hold the drift as you need to keep power to the front wheels to maintain and control the drift. TC won't let you.