Prius Traction Control Complaints on the Rise

Mustangs are RWD, PRIMARY braking is on the front.

 

This really belongs on a different thread than traction control. They also tested a camry which is similar to the saylor Lexus. It stopped faster than the mustang. It also took 3.3 seconds of pressing the start button to turn off the car, which might be long enough in a panic situation to think the engine would not turn off. If the brakes were working properly AND they were held firm and not pumped then they should have stopped the car. There were previous complaints on the car and the story, so the brakes were likely damaged before the fateful ride. Toyota is correcting things on the vehicles and putting in brake override. This is the solution the NTHSA had requested before and many auto companies had already put in cars to prevent this type of accident.

The gen III does not have a text book brake override but software to protect the drive-train does act as a brake over ride as long as the driver is not pumping the brakes and holding the accelerator. Toyota brake over ride is software based and software is often implemented to allow for wheel spin at low speeds. The recent investigations could not find electronic problems to explain the sykes case. We can generously say he might have been pumping and letting off and something unseen was holding down the accelerator.

 

With my '04, the Snowflake would stay on most of the winter, and proved very annoying. I had an easy way to make the Snowflake disappear: a piece of black electric tape over it

 

Thanks.. I feel like I have an iPhone3 now. lol

 

"..brakes were likely damaged before..."

There is a strong indication that Saylor had 2 UA incidents that day. Witnesses say they saw the saylor vehicle parked on the center median with hazard lights flashing and smoke coming form the front of the car.

We might "presume" from that that Saylor had somehow overcome the initial incident but for some reason decided to proceed. In any case the brakes would have been compromised due to the initial incident.

 

"...software to protect the drive train..."

Why wouldn't the standard engine, ICE, rev limiter suffice for that..?

Once TC begins use of the brakes to abate or prevent wheelspin the engine must be dethrottled fairly quickly rather than risk brake rotor overheating and subsequent warpage.

But again, the Prius does not have, literally, a brake over-ride system. The HSD system, by default, has a "virtual" brake over-ride in that it ALWAYS(***) reverts to, enters regen mode, with brake use.

*** Unless the brake light switch fails or the ECU firmware gets "live-locked" in the CC "accel" mode.

 

What's your point? It makes no difference whether it's FWD or RWD or AWD - primary braking is on the front.

 

That is how the TC works in my FJ Cruiser

In 4L, it is also used for A-TRAC

 

The difference with the prius is motors and electronics are involved and it has been stated that the traction control protects these systems. I do not know the physical limits. Once traction control kicks in it does reduce throttle on my car. Is it to protect the brakes or the mgs, I don't really know.

This is from the horses mouth toyota
Newsroom : Toyota Prius Vehicle Throttle and Brake Systems: Myth VS. Fact / Toyota

This is software based, and we have no evidence of an electronic problem. In fact we have recently had an investigation that found no problem. The software is independent of the brake light. It is software though, and a bug could possibly happen. If you read the link you should apply firm pressure to the brakes and if not slowing put the car in neutral.

Oh and from the same link on how the brakes and the throttle will work without the software interfering for the snow start case.

 

I'm also old enough to remember having problems with broken return springs on carb's. That happened way more often than modern UA issues. Had it happen to a couple of old clunkers I used to have as a teenager

But as far as TC, it's quite clear that at least in my '04 Prius, it was anything but

 

Traction control should have a switch option. Other car companys do.

 

That return spring was a mechanical device that most anyone could accept a failure.

To the general public software remains "behind the curtain", our of mind, and failure just cannot be accepted in the public mind.

If the general public is ever given even the slightest reason to doubt the reliability, infallibility, of software coding then how many people would get aboard a 777..?

 

With most cars the front brakes can easily overcome wildly spinning, DRIVEN, rear wheels/tires. The rear tires can do what they will, the fronts will still "lockup".

 

Yes, and if damage to the drive train really is an issue then lower the rev limit to ~2500RPM at the same time.

 

My post here won't solve this problem, but I hope it rekindles interest.

I believe that this is a safety issue.

I have had my 2007 Gen 2 Prius complete shut down on a fairly slippery compacted-snow approx 5% grade. On one occasion, I took out my 1992 Accord (automatic transmission, no traction control, no ABS, no stability control and with all-season tires similar to those on the Prius) and, driving carefully, drove right up this hill.

More of a safety issue is pulling out onto a road with rough, wet, sandy, or gravelly pavement. The stuttering of the Prius is completely unnerving, especially if there is an oncoming car. Again, my Accord will pull out smoothly and much quicker with little or no wheel spin.

I can understand that the drivetrain might be damaged or overly stressed if unlimited wheel spin were allowed. However, the drivetrain must be able to allow significantly more wheel spin than the current limit. A less aggressive traction control would surely enhance stability in the above conditions.

I'm not sure how to get Toyota to do something about this, and it looks like Consumer Affairs already tried and failed 3 years ago, but I just had to vent here.

FYI, here's part of Toyota's 2009 response on this issue:

"A vehicle without TRAC in those conditions," Kwon added. "would probably just start spinning in place and eventually spin out of control. In my opinion, it's better to have the vehicle stop then to have the wheels spinning and out of control."

It's been cited elsewhere, but the rest is at:
Winter Weather Warning for Prius Drivers

 

You didn't list what tires you are running. Most Prius owners that run appropriate winter tires do not have a problem. Maybe you should look into running a winter set. It's not safe otherwise.

 

A day late and a dollar short. Toyota already improved traction control on the Gen III. As for a Gen II refit, it won't happen. There isn't an easy fix for the Gen II.

Tom

 

Really? So that what ... you can disable it ... over rev the ICE, burn up the HSD, and then cry when that happens?
Oh yea . . . I can see it now.



Everybody and their 2nd cousin will be wanting a refund for the purchase price of their car - because the Prius was built where it could easily self destruct every time some poor poor unsuspecting slob decides to just sit there on black ice ... trying to continue on ... uphill ... and over-rev all the way to high heaven. Oh yea - great idea. Sorry, but modernly - manufacturers have to build things so that they're idiot proof. Otherwise, if they don't, the manufacturers will be sued out of existence in no time.

.

 

Umm if you have to deal with step hills and deep snow.....DON"T BUY A PRIUS

 

hill, didn't you read my post? Here's a quote:

"I can understand that the drivetrain might be damaged or overly stressed if unlimited wheel spin were allowed. However, the drivetrain must be able to allow significantly more wheel spin than the current limit. A less aggressive traction control would surely enhance stability in the above conditions."

How do you interpret that to mean "over-rev all the way to high heaven"?

At least your point about manufacturers having to idiot proof the car was valid and useful to those who might not have considered it. However, a greater tolerance on the traction control could likely be provided while still keeping the car sufficiently idiot proof.