How to disable VSC?

No, not really..., I used to go on speed tracks also but just for fun,

I understand you, the only thing that shocked me was that you said you would sue Toyota if you were in an accident...
You know the system is here, you know it may kick-in, you know the behaviour when this occurs, so take extra precaution...

I don't think your car is faulty, I had the same behaviour, TC also occurs when regen braking FYI it's much worse, feeling like the car stopped braking suddenly...

Maybe your tires are not the best, in France we have Michelin tires and they are really good but I read here that some of the standard tires in US are quite slipy...

To minimize the risk, just allow a little speed before flooring the pedal, I noticed that TC kick in while the car is at stop when you floor right on.... the electric kicks in then too much torque TC engage...
If you are more progressive, when the electric kicks at max torque the car is already moving and there is less chance to slip....

 

I actually have 215/45 ZR17 BF Goodrich g-force Sport tires. They are pretty impressive. Night and day compared to the crap OEM tires.

And yes, I would sue Toyota if that horribly ineffective/defective assist system CAUSED me to crash. I've been lucky 3 times to have not crashed due to the dramatic action the car took when it should NOT have.

Feel fortunate that you have not experienced the action my car has taken when it shouldn't have. Perhaps my system actually is not operating properly because the system activates practically daily. Granted, I do drive on pretty shitty, but still paved, road. This activation is almost always just annoying with the power shut-offs and the unexpected decelerations. However, when you are simply trying to get on the road and the power stops??? No. That's flat-out dangerous. And when turning hard right to moderate, but immediate, left and then having the car literally THROW me really hard left all the way to smack dab in the middle of the oncoming traffic lane is truly dangerous. If there was an oncoming car right there, the assists would have CAUSED a head-on collision. Yes, I WOULD have sued. BIG-time!

It really should be Toyota that initiates a recall or at least a disable patch. I will say it again, the assists in the Prius specifically are absolute rubbish. You would have to be a really crappy driver to benefit from the level of actual ASSIST it provides, and a literal magician to get out of the havoc it can cause.

 

Yeah, VSC is nice...until you live in a place where it SNOWS!! I got stuck for the first time in my life in 6" of snow because it was physically impossible to rock my car 1/2 inch at a time. There should be a switch to shut it off (like in the Honda we bought today).

 

It will rock. I've rocked mine out of snow many times. The technique is a little different, but once you get the hang of flipping the shifter knob back and forth it works pretty well.

Tom

 

When you have the Prius hanging on its belly on 6 inches of snow with 5 inches of ground clearance switching off traction control will have little benefit.

 

Looking at the schematics, all the fuses for VSC/TRAC are shared with ABS, so if the car even lets you drive it with all these fuses removed, there would be plenty of critical warnings displayed.

 

I found that out from driving Jeeps. One wheel, two wheels, or all four wheels spinning, it's all the same when they are up in the air.

Tom

 

Well, I have a Jeep too. Lol, and I too know what it's like to have its belly resting comfortably on some nice firm mud while all 4 locked wheels spin at a nice uniform speed, failing to move the vehicle one bit. At least that was solved with bigger badder tires and a lift kit.

However, my Jeep never just cuts the engine off when pulling out of certain kinds of driveways into traffic or simply driving over potholed/patched surfaces. I just find it hard to believe that Toyota, having done such a horrible job with the Prius' VSC/TRAC, won't even give an option, or even a factory disable for it.

 

Yep, killing traction control is the answer.
This car has no traction control but I guess like the Prius it has a big bag of torque.
Watch from second 24 on to see how well this car gets going without traction control, wonderful!!!

 

I have two cars: a volvo xc70, and a prius. Both have traction control and stability control (DSTC, ESP, or VSC, or whatever you want to call it).
There is a day and a night difference in the behaviour of the control systems in both cars. In the volvo, they are working extremely well and amlost doing magic. Traction control only jumps in when really necessary, and DSTC is a little miracle on snow.

In fact studies are showing right now that ESP (DSTC, VSC, ...) is one of the most life-saving features, at the same level as safety belts.

In the prius, they are usually simply counterproductive. Especially the traction control is sometimes simply putting you in a dangerous situation. I can only guess that this behaviour is forced by by the specific driveline of the car.

 

The behaviour is due to the designers not wanting to waste energy by applying drive to the wheels while simultaneously applying the brake to a drive wheel. That's why they cut power to both wheels. Maybe it needs a Torsen differential.
Any Toyota parts people who might be reading, will the torsen diff from the early RAV4 fit in the Prius differential? Was there ever a torsen diff in the corolla that might fit?

 

If that's the only reason, then that is truely a shame. There are plenty of occasions where the prius traction control cuts power too early and too long, potentially bringing the car in a dangerous situation. In my view, if the only reason would be to somehow save a little energy, this would be a terrible design flaw. Safety first.

The whole purpose of traction control is actually to *increase* the ability to accelerate on a slippery surface, especially with high torque front wheel drive cars. That's why modern traction control systems indeed can brake individual wheels, compensating the functioning of the differential.

I can live with the horrible traction control system of the prius if it is somehow required by the specific design of the hybrid driveline. But not if it was some deliberate choice.

 

I know this is old, but I couldn't resist:



and

Good luck with the VSC.

 

The primary reason for traction control on the Prius is controlling all of the torque from the electric motor, which could easily destroy the PSD and drive components. Even though it's needed to protect the hybrid driveline, it would be nice if it improved traction instead of causing issues.

Tom

 

I'm confused. What exactly is the traction control protecting?

I thought that it was protecting MG1 from overspeed, but if the ICE is running at all that doesn't seem very likely unless you deliberately set out to damage the drivetrain rather than just attempt to accelerate quickly in low traction conditions.

If the above is true then disabling the traction control temporarily may not be the very harmful thing that we have been led to believe (remember that it does not allow the ICE to stop). Certainly if I ever get stuck in snow I shall not hesitate to disable traction control in an attempt to free the car (gently).

 

I have heard that before and I do realise indeed that spinning wheels are potentially dangerous for the prius, because of the planetary gear system. But I don't necessarily buy this as a fully satisfying answer.

Why does it have to be a yes/no system? Right now, if my prius detects any wheel slipperage, it simply shuts of all the power, for approximately a second.
I can't imagine that it would not be possible to design a system that avoids the wheels from over-revving, without immediately cutting all power for a while. With the instant, computerised control of both electric engines, it should be possible to make it even better than in a conventional car. My impression is that, at slow speeds, the hybrid system can vary the torque quicker than a gasoline engine.

It remains my impression that this is simply a part of the car that toyota hasn't spent sufficient attention to. Maybe they were too afraid of damage to the drive line, and designed the system to be overreactive.

 

Firstly, if you have a newer Prius, disabling traction control will not help you get unstuck in snow. The newer traction control algorithm allows for wheel spin. If you are stuck with traction control, you will most likely be stuck without it.

Secondly, without traction control, you will not be able to "gently" attempt to free the car. The low end torque on the Prius is unlike anything any of us has ever driven in terms of ordinary passenger cars. Without electronic speed limiting, MG2 can instantly over-spin the drive wheels.

There are really three issues behind needing speed limiting traction control with HSD: 1) Control. Without it, most of us would burn off our tires even on dry pavement (well maybe not, but there would be a lot of squealing and burning out); 2) Over-speed. It is very easy to over-speed parts of the HSD without speed control. In a low traction situation, you could easily over-speed MG1 even with the engine running. MG2 can change speed much too fast for the speed of the ICE to catch up. The damage would be done before the control system could do anything about it. Still, you could spin your tires in snow at a rate equal to about 60 mph without damaging MG1, so that's not the key issue unless you drive like an idiot; 3) Shock loading. If you spin up the drive train, then hit a dry patch, the shock loads are increadible. Limiting wheel speed limits the potential for shock loading.

The real issue comes down to traction. If you have good traction, then traction control is not a problem. If you don't, then you end up posting in a thread like this. Tires are a key element. The Goodyear (lack of) Integrty tires are not a good winter tire (I don't think they are a good summer tire either, but that's another discussion). Without good tires, disabling traction control will just produce more wheel spin. In rare cases wheel spin can be used to move on ice and snow when you are able to burn down through the surface to something substantial. Generally this doesn't work in real winter conditions.

Real traction control, unlike the speed limiter on the Prius, provides a means to improve traction. Generally real traction control engages the brake on a spinning wheel to force driving power to the other wheel. It acts as form of limited slip, which actually improves your chances of getting up a hill. The Prius system doesn't improve traction, it just keeps you from spinning uncontrollably, which is useful, but not overly effective except in the sense that it prevents damage to the HSD. While the Prius traction control system doesn't help much, it doesn't hurt much either. Generally people blame traction control for a low traction situation in which they wouldn't move with or without traction control. It's a lot like the comments we see about VSC causing a driver to lose control and nearly kill themselves. Generally what happens is the driver loses control and VSC kicks in and tries to save him, but the driver sees it the other way around. Perception is a tricky thing, and when people get a notion in their heads it's hard to shake it out with logic and reason.

Tom

 

I fully agree. I never made the claim that it is fully optimized. The traction control system on the newer Prius (like yours) does this to some extent. It will allow low speed wheel spin. However, it could do a lot better job. Diesel-electric locomotives use limited slip control to achieve maximum traction going up steep grades. They actually allow the steel wheels to slip on the steel rails, doing so at a rate that optimizes traction. If they can do it with a locative, they can do it with a Prius.

I think you hit the nail right on the head when you say this is an area that requires more attention. I hope Toyota has improved this on the 2010 model.

Tom

 

I think it's really the third point that matters to me. I generally do not experience any problems with loss of control in dry (or even wet) conditions, the traction control indicator does not light. Regarding over-speed, although MG2 can generate a lot of torque, it will only if I instruct it to do so. In snowy conditions all of my control inputs are small and gentle.