Slippery hills vs. TRAC

Well, I'll take a stab at it:

If you're allowed to use studded tires, they will provide better glare ice traction. You mentioned the slippery driveway. In Manitoba you can use studded tires, but the Condo Association where I live prohibits them in the heated underground parking.

I had Dunlop Graspic DS-2 last winter and they had a huge improvement in snow and especialy ice traction over the Michelin Harmony tires. This winter I have on Yokohama Ice Guard 10 and they offer BETTER snow and ice traction compared to the Graspic.

My parents have a 2003 Buick LeSabre and I got them 4 studded Cooper Weathermaster ST/2 tires last fall. The Buick with the studded tires has much better glare ice traction again compared to my Prius running the Ice Guard tires. About the same snow traction though.

Always put 4 winter tires (Studded or studless) on a vehicle. If you just put them on the front, the rear end could fishtail on slippery surfaces and cause you to lose control. Just put them on the rear axle and you'll have problems turning, stopping, and accelerating again.

I found that Trac is equally intrusive in reverse as it is in drive. With the proper winter tires, I don't have to worry about taking a "run" and possibly crashing into something.

The Trac is tightly integrated into the Prius. I would worry about CEL's and even destroying the power split device. Don't disable it.

 

I have Michelin Xice tires that I like pretty well. Studded would be better on ice.
Some other non-studded may be slightly better on ice, but unlikely as good in rain and dry pavement.

If I get stuck I have Spikes Spiders I can cliip on to get up a hill. They are chains that are easy to put on and take off. So far I have not needed them, but came close to, a couple of times last winter.

 

First off, I can't stand studs. They are noisy and on top of that they do huge damage to the public roadways. The way most local and state government work, they don't bother to take care of the roads and as such studded tires do damage that isn't corrected on a year in, year out basis.

Most studdless snow tires perform as well as or better than studs in most winter driving conditions, including ice. Michelin x-ice are excellent. Bridgestone Blizzaks also come highly recommended.

I have a friend with a rear drive Nissan 300zx and they lives in a city made up of hills. Snow and ice are a problem there and with regular tires the Z is a terrible winter car, but thros some blizzaks on it and it is a great winter car. No studs needed.

Creeping up the grade probably won't help you much. You might be better off to take a running start at it. I have another friend who lives up an unpaved incline and he has extreem difficulty getting up it after it has snowed and for many weeks thereafter. He has a Grand Am which is the most unsure front drive car I have ever seen, and even with traction control off and a good set of M+S tires on it, he can't get up his hill, running start or not. This year he is going to buy studless snow tires and hope for the best.

You cannot defeat traction control on the Prius. It has to do with what a free spinning wheel could do to the PSD in terms of RPM limits of the connected devices. As soon as the Prius senses slippage it stops the slippage to protect the powertrain.

 

BUT, you can disable it. Which I found out this morning here in Mass was necessary or I couldn't have driven out of my driveway which is barely any incline at the top but with only 3 inches of snow I couldn't go anywhere. It basically kept slipping even with the slightest pressure on the accelerator and then the car would hold back way too long to be able to get a bite under the tire.. But thankfully I had read here on the forum a little while back how to disable the traction control. I couldn't find the link to put here but it's easy.

1) Turn the car to ignition by pressing START twice without pressing the brake.
2) Floor the gas pedal two times (two full top to bottom pressings)
3) Make sure the Emergency brake is on now and put the car into NEUTRAL
4) Again press the gas pedal two times
5) Push PARK and press the gas pedal two more times
6) Now put your foot on the BRAKE and press START one time while holding the brake down.
Now the car is started and ready to go. You will see a flashing red symbol in the upper left hand corner of the Screen. This is the mode for when you get your emissions tested. This allows the front wheels to spin without the rear when the car is on the machine.

When you turn the car off this resets back to normal. Without this feature I wouldn't have been able to get out of my driveway this morning. I also drove up some side streets and found with it on I was almost in accidents because people behind me were trying to get up the hills faster but I was slowing them all down. Yes better tires would help but no tire is going to make up for this OVER SENSITIVE traction control system. My friend had a SAAB 5 yrs ago with a similar system for the snow and with it on, the front wheel drive only car can make it up steep inclines with a foot of snow. Without it, it can't get anywhere.. So why in the world couldn't Toyota do the same thing?? Anyhow I hope this helps some of you get out of some slushy situations this winter.




You cannot defeat traction control on the Prius. It has to do with what a free spinning wheel could do to the PSD in terms of RPM limits of the connected devices. As soon as the Prius senses slippage it stops the slippage to protect the powertrain.

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If this feature does work..... I would think it is only for emissions testing whereas the rpm is limited since they tell you how far to press the gas to do thier test.
In real life if on the snow.. I think you could damage the electric motor by exceeding the rpms it rated for?
I suppose if you were very careful about not spinning out of control, you may be ok.. but I an not an authority on the subject, but I have read about how Toyota has placed this "protective measure" to prevent damage.

 

Depending on your situation and the road conditions where you are, if you have the OEM tires on now you might want to try a set of good all-season tires. They would give you better grip and control than the (mediocre) OEM tires, but you would not lose as much in dry-road handling and mpg as you would with real snow tires.

My own experience of the traction control is slippery intersections in Fargo in winter. (I had the Prius for 1 1/2 winters in Fargo before moving here.) At first it was odd: I'd step on the gas and nothing would happen. Where my old car would have spun a tire, the Prius just sat there for a brief moment, and then moved forward very slowly. I could floor the pedal, and the car would still just creep forward. But the wild thing was that other cars were taking much longer to get going. I actually got through the intersection faster than most other cars. Only the 4WD or AWD cars could compare. Of course, there were no hills. Fargo is flatter than Kansas. But my guess is that if you disabled traction control you'd just spin your tires. Better tires would be the thing.

 

We live on a gravel road (Maine) that ices up before any of the paved roads do and holds snow long before the paved roads will. Plus, it's a steep incline. The Prius makes the climb when I'd only attempt it previously with 4wd. Too, I'd sometimes tow the wife up the hill in her (pre prius) vehicle.

Now I'm not saying the Prius is the equivalent of a 4wd, but if one can drive on snow I am saying that it's way ahead of any standard ICE powered vehicle w/o TC or VSC. It depends on throttle control in my experience. Spin the tires in an ICE vehicle and you lose traction and steering, same with the Prius because of the TC, except it'll keep you from sliding off the road when you lose traction; you maintain steering control since you don't spin. Back off the throttle short of spinning and the Prius responds and climbs like a banshee. Sure, accelerate when you can to develop momentum, but know when to back off. TC will inform you if you aren't white knuckled and are paying attention. Attempt the "spin the tires" routine and you'll be SOL. The Prius is really good on responding to light throttle so the experienced foot can come through and deliver.

That experience was on the OEM tires last spring.

This year we have Graspics and even the wife has no problems. That based on this last storm. Yesterday we had an ice/snow storm and she did great, experiencing no problems; she would have with her old vehicle (which I now drive; yup, there was spinning with a too heavy foot, mine). Spinning does nothing for traction and throws the vehicle into a skid (fwd). Traction control would just enable it to cause a different sort of problem if the driver compensated by giving more or the same throttle. Instead, give less throttle. I'm not saying to crawl, but use an educated foot. Don't expect the vehicle to drive for you, you still need to know how to drive in crud. We haven't traded $ for driving skill just because we drive Prii.

Try to spin the tires if you wish, but you won't, and we'll all just keep reading these posts all winter. Much better to learn to drive in snow and ice w/o spinning to keep the TC inactive. Some road conditions can't be driven in, and that may be another thing that's being experienced. Take the hint and stay home during those conditions, or find an unoccupied parking lot and practice. No one earns enough in one day (legal income) to make up for a collision and damage to oneself and others.

Sorry if I wasn't PC enough, but I read these posts last spring and frankly, still don't understand them unless the posters don't know how to drive in terrible road conditions to begin with. Just drive according to road conditions/skill level or stay home. The Prius is a phenominal vehicle in slick road conditions. I've driven ours in conditions this past summer that COULD have given lousy TC results (loose gravel), but by not pushing the throttle had no problems. Snow and ice is no different. These are our normal conditions, good traction is a temporary, short lived condition for us, most of our year traction is the pits. FWIW, all this summer the wife practiced getting up the hill w/o alot of power, ie: in EV mode, practicing for winter and ice. She isn't fast getting up the hill, but I have no doubt my days of towing her up the hill are over. It's a short step from climbing in EV mode to gaining momentum and backing off the throttle for ice/snow conditions. She proved she has the technique this last storm.

Trust me, if my wife can do this anyone can. She's the first to admit she doesn't drive in marginal conditions. She isn't a good driver in inclement weather but admits she had no problems with our icy roads yesterday and they were horrible driving conditions. This is untypical of my wifes driving ability, the only thing I can attribute it to is the Prius. She'd tell you the same thing.

 

Has anyone succeeded to "implement" this scenario on a 2005?

I tried on a 2005 Prius delivered in France and I can't get it to work: no flashing red symbol in the upper left hand corner. About instruction 3: does switching to Neutral produce a bip ? Instruction : it does say press PARk "AND" press gas pedal ... that is together isn't it

Alain

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It's probably not accurate to say that disabling traction control will damage your power train. I mean if you get a Prius with package #3 or lower you don't get traction control. I suppose you can claim traction control has the effect of providing extra insurance against having you wheels spin away and then suddendly catching, but that applies to all normal cars with no traction control.

 

Actually, I believe any second generation Prius has traction control (I'm not sure about first-gen, but I think they do too); you may be thinking of the skid-suppression system whose acronym escapes me at the moment, which kicks in when the car detects a lateral skid, or a similar orientation-related loss of traction, in which the car will brake individual wheels in order to restore control to the driver.

Traction control, on the other hand, kicks in when torque exceeds friction, causing the wheels to spin- and the electroc motor has a lot of torque!

 

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I haven't tried your technique of disabling the traction control yet. Just wanted to check. Usually if you just press power twice without pressing the brake you just get the power turned on but the engine is not enabled, correct? I wanted to make sure when I start flooring my gas pedal twice I'm not going to be hearing an engine reving like wild. During your sequence of steps when does the engine become active to move the car and when is the engine inactive?

Also about your comment on traction control, if traction control is there to protect from over reving what about the Toyota Prius that do not have traction control? So if you do what you are doing to disable the traction control it would seem you run no more risk of damage than driving a Toyota Prius that doesn't have traction control. Remember, although it's not that frequent, Toyota dealers have sold Prius's without traction control.

I also did some research on complaints about other makes of vehicles of traction control and it appears that problems that are sometimes experienced with the Prius traction control are typical. I've read of Cadillacs, Buicks and Oldsmobiles owners that noticed in some cases they were better off spinning away tires than having the traction control pull back on the throttle. Also there have been incidents where at highway speeds or even coasting downhill without pressing the gas traction control would go on. The drivers would be forced to drive slower. There was some commentary that in some cases possibly salt accumulation might eventually get into any poorly protected sensor connectors and short out the sensor making traction control think a wheel is locked.

The same kinds of issues also exist for anti-lock brakes. I know that ralley race car drivers don't like traction control or anti-lock brakes because they prefer full control over their car and can manually achieve the effect of traction control and anti-lock brakes as needed. For example in deep snow or gravel I've heard that your better off skidding and piling up stuff in front of your tires. Of course this is for those who are out to drive with high risk in order to win an off road race.

 

Traction Control is standard on all 2004/2005 Prius cars. It limits wheelspin on slippery surfaces and is VERY intrusive.

The vehicle stability programme is optional, it may prevent a slide or loss of control in an aggressive emergency steering input. My Prius has it but the base model does not.

 

Is it TRAC or the optional VSC that makes the Prius such a good snowmobile? (according to some, with the right tires)

 

It is more a combination of all 3 driving systems that make the car a snowbeast.

TRAC to start going in slippery conditions
ABS to stop in Slippery condition
VSC to corner effectively in Slippery conditions

but as always they all rely on the friction genterated by the tires, the more friction, the more it can manipulate the friction.

 

I also tried this on an 05 delivered in the USA and couldn't get it to work. At step 3 the car stays in Park and never goes into Neutral.

 

Forget about the E-brake and use the real brake instead, since the car won't go into neutral without pressing the brake, as is normal. The E-brake does nothing. I've also heard that this defeat may only work on Prius in the US, please let us know if it still doesn't work and that is the case...

Per http://www.seattleeva.org/wiki/User:Rjf/Pr...raction_Control
WARNING: The shop manual apparently states in no uncertain terms that this procedure must NOT be used to drive the car as damage to the transmission could occur due to traction control being defeated.


* Follow the sequence below (quickly - within 60 seconds)
* Set Ign switch to ON, not READY (Power button twice, no brake)
* While still in "P" fully depress the gas pedal two times.
* Select "N" fully depress the gas pedal two times.
* Select "P" fully depress the gas pedal two times.
(LCD display will indicate a !Car! in upper left corner of screen)
* Turn key directly to "start" to start the engine (brake+start button)

It forces the ICE to run continuosly and defeats the traction control system. Normal operation returns after turn off and reboot. Unlike EV-Mode this is strictly a diagnostic function and should not be used under normal situations.
Thanks to Peter Rawlinson for posting this on the Yahoo Prius_Technical_Stuff group.
http://autos.groups.yahoo.com/group/Prius_...f/message/13315
More discussions can be found here:
http://priuschat.com/Thinking-about-discon...rol-t12860.html
http://autos.groups.yahoo.com/group/Prius-2G/message/46367
http://autos.groups.yahoo.com/group/toyota...s/message/90032

 

Thanks , it does work for a Prius 05 delivered in France this May.

I can't understand why the original instructions posted were so wrong.

These "things" need to be spelt very precisely. Never heard of E-brake but I found out that it is the Emergency brake

One thing though, for step 3):* Select "N" fully depress the gas pedal two times.
it implies that it should say ut your lefy foot on the brake and depress the gas with your right foot two times. Didn't figure that the first time :-(

Alain

 

I have the shop manuals and have read the warnings on disabling the traction control. This feature was put there for one reason for emissions testing. The instructions were not put in the owners manual because you can break the car if you do this. You may get away with it but then you may over rev the HSG. I think better tires would be the way to go improve tire grip on the road and let the Traction Control do its job. For right now I am driving the Explorer on snowy days and that is ok in this climate where we get little snow. If we get a atypical winter I will get snow tires. We can have studs in this state but I would probably not go that rout. I will not be taking the Prius over the pass in winter.

 

My house is on the top of a mountain and we routinely get 1-2' snow drifts after only 4-6" of snowfall. I too live on top of a hill that ices over during the winter time, add 1" of snow and I CAN'T get up the last 1/4mile to my home. Due to my driving 110 miles round trip to/from work and the high cost of gass I have had to give up my 4wd truck.

I have Bridgestone Blizzak snow tires, I do not have an alternate vehicle and leaving my car on the side of the road is NOT an option as snow plows will destroy it.

Why is is that so many don't seem to understand this and keep insisting that 'better' snow tires are the only alternative when disabling the TRAC for me is the only viable option? Neither the crawl nor accelerate methods work and numerous times the car has slowed to a STOP due to this overly sensitive traction control - in my more extreme conditions.

I have not tried this sequence yet but will before the need for it arises.
Thank you for posting this information!