Can traction control be disabled?

I have a whole stack of microcontrollers just looking for something to do.

Tom

 

I bet you do too ....

 

I also bet you have some FPGA's looking for a good home

 

I have a whole tube of one model that I bought for a project but never used. That model is mostly obsolete now, but I can't make myself toss them out.

Tom

 

I'm pretty sure in a dark corner of the basement, we both have "The Box of Misfit Electronic Parts"

 

Well, the Trac in my FJ appears to have been designed right ...

 

Yep, it is, and I've gone into painful detail in other threads to highlight this difference. As I can readily drive them side-by-side, it's easy to prove or disprove certain points

Eg: the brakes are actually used in the FJ Trac. It's confusing in the Tundra, as Toyota calls it "LSD" which conjures up a mental image of clutch plates inside the differential. The Tundra "LSD" is an open diff, it also uses the brakes

When wheelspin is detected, the brake is applied to the spinning wheel. In 4L this system can be made four wheel and very aggressive, by engaging the "A-TRAC" button

With one side on glare ice and the other side on dry pavement - a common occurance at intersections here in winter - my FJ has no issues whatsoever moving. Yes, it has studless Toyo Open Country G-02 Plus winter tires, I am switching to factory studded Nokian winter tires for next winter

With the studded tires on my Prius, a similar intersection is ok but not ideal. The studded tires really help a lot. With "all season" tires, my Prius would remain motionless

 

My Prius and I have argued about the merits of the traction control for some time. Like many, I live in the mountains and have snow and ice to contend with. The Prius is not too excited about driving uphill in slick spring snow! Fortunately, when the weather is known to be nasty when I leave the house, I have the choice to drive my FJ instead of the Prius. It is those sneaky storms that make getting home fun.

I wish we could figure out how to get the Toyota engineers to give us a Traction control “Off†button. The Traction Control logic they use “The goal of the motor traction control is to restore traction when wheel slippage on a snowy road is detected, for example, and inform the driver of the slipping situation.â€( From the Toyota website) is great for restoring traction, but it is sadly lacking in giving us the ability to drive the vehicle up a hill.

It is the common argument that the “Traction motor has so much torque that the mere mortal human cannot control the power output and therefore we have to have computer to safe guard us!†Whether or not that is a true statement is immaterial because their solution is not right for every situation. To meet their goal, their solution is great. To meet the goal of getting vehicle up a hill, their solution does not work.

To meet both goals, leave the normal Traction control for normal operation. Then give us a traction control defeat switch that changes the protection logic from the current system to one that actually watches for wheel overspeed. Cutoff the power when the wheel speed sensors see overspeed conditions. Cutting off power when the wheels are turning at 2 miles per hour is a little silly. (Actually more than a little silly). Give me the ability to actually drive the vehicle up the hill. As the wheels slip trying to get traction while digging through the snow, don’t kill the power. I know my Prius is capable of driving 80 mph down the highway. So I don’t think it is reasonable to be terrified of slipping the wheels at 2 mph.

In my experiments to kill the traction control I have found no way that I can make any effect on it. It is really deep seated logic in their system. I think the only way to get there aftermarket would be when someone hacks the software to the system. So for now, my only solution is to run aggressive, studded, mud and snow tires and carry tire chains.

 

You can defeat the traction control in the Prius by switching into inspection mode. The instructions are here on PC.

If you do this, be careful to not hurt the drive system. I would be interested to hear about how it works for you in the mountains, assuming you give it a try. One of the questions is whether traction control is causing the problem, or whether traction control is simply a symptom of poor traction. Disabling traction control will give you a chance to test this.

As for having a switch to disable traction control, that only makes sense if you can't design it correctly in the first place. Even without selective braking, the control system should be able to do better than a skilled driver. Diesel locomotives have used systems like this for years to provide optimal traction. The process is called controlled slip, where the driving wheels are allowed to slip just enough to maximize traction.

Tom

 

I don't think these instructions actually work. I tried to get them to work for quite awhile and finally gave up on them. They appear to be actually written for a different vehicle.

The major flaw in the Toyota system is that their traction control logic has to be ideal for every drivinig condition in the world! Real life doesn't work that way.

 

I actually tried many ways to kill it.

The inspection mode didn't work.
Unplugging one of the wheel speed sensors didn't work. - The logic was that the system would realize it did not have a full set of sensors and would turn itself off.
Pulling fuses didn't work. - The traction control is somewhat related to the ABS system since the wheel speed sensors plug into that module. I hoped that killing parts of the ABS system would eventually kill it. No luck.

It was interesting that throughout the testing other parts of the vehicle operation would act weird. For instance, when you pull a wheel speed sensor, the vehicle pulls much harder against the brakes when in drive and stopped.

I think the power reduction part of the traction control system in deeper than wheel speed sensors.

 

Since you also own an FJ, I'm sure you're aware there is no Trac defeat button. The only way to defeat Trac in an FJ auto is to shift into 4L

However, with A-TRAC, you can then use a very aggressive form of four wheel traction control. In truly bad situations, engage the rear differential lock

I find the Trac in my FJ very smooth and easy to live with . Combined with winter tires, I leave my FJ in 2H almost all the time

With my Prius, aggressive European-designed studded winter tires took care of most of my Trac complaint

 

If they would have just put some of the FJ smarts in the Prius I would be in heaven!

I also run real aggressive studded snows on all 4 corners of the Prius and it takes care of me all winter. It is the spring where the Prius starts to lose it. The spring snows are slick enough that the tires start to slip then it is all over. I hate pushing the car up the drive when I know it has the capability of driving there.

I wish there was a way we could get enough voices together to get the Toyota engineers to listen and make a CPU programming change. Give us a traction control override that allows the system to pay attention to overspeed instead of a tiny difference in wheel speed. Wheel speed difference is great is normal driving conditions. It is the abnormal conditions that need an alternative control logic.

 

Yes, I agree. The Trac in the FJ is very well thought out. Perhaps the single most important difference when one compares the Prius and FJ Trac is this: the FJ will also apply the brake to the spinning wheel

That common winter situation around here: the center of the lane is bare, the curbside edges are icy. With the FJ, the side on the icy portion the brake is applied to that wheel, and the wheel on the bare portion easily moves the vehicle

 

I searched for this topic after last night's snow strom, which was my very first snow driving experience with the '09 Prius we purchased this past May. I live in Colorado and our home is up a winding moderately steep hill. Before even purchasing a Prius, I read this and other forums trying to get a handle on how the car did in snowy conditions. I also talked with any Prius owner I happened to run into locally. The general consensus I got was that the Prius could handle snow just fine with a good set of snow tires. I put a set of Michelin (x2's I believe) on.

Last night we went out during a snowstorm. When we drove home at around 9 pm, it was snowing and there was about 3-4" of fresh, powdery Colorado snow piling up....the snowplows had not been out yet I guess. Anyway, our hill had not been plowed. Halfway up, with another neighbor on my tail, my Prius got stuck due to the stupid traction control. The indicator light on the dash was flashing continuously as I drove up. Then, we just stopped. I had to back down (after my neighbor backed up) and try it again from a running start. This time, we JUST BARELY made it up.

I traded a Subaru Outback for the Prius. The Subaru NEVER, EVER got stuck ANYWHERE! So, now we are faced with the possibility of having to trade the Prius for another Subaru as I have NO FAITH that the Prius can safely get us through the winter and spring snows... live and learn.

Conclusion: DON'T BUY A PRIUS IF YOU LIVE IN HILLY, SNOWY CONDITIONS!! It is most definitely the worst snow car I have driven in 40 years of snow driving.

 

Sorry to hear that. Just be thankful you didn't have my '04, it had far more sensitive Trac

For those who live in snowy/hilly terrain, all I can suggest is a test drive under those exact same conditions. That is the only way to know. Once you've bought it, you're more-or-less stuck with it

Also, don't be surprised if the Prius Fanboys call into question your winter driving skills. They certainly did with me, although I learned how to drive in extreme winter conditions

Using techniques that worked well on previous cars, backfired on the Prius. Running aggressive studded snow tires helped, but once the car started to bog, I was done

If only it had a Trac-defeat button. Even if it didn't truly defeat the Trac, but just detuned it

Apparently, the 2010 Trac is easier to get along with. The only way to know for sure is to test drive one under similar conditions

I should point out that in 2H, the FJ Cruiser Trac can also intervene. But shift into 4H, and the Trac is made much less sensitive. Shift into 4L, and the Trac is disabled

 

I live in Aurora Colorado and drive to Colorado Springs to work. I also did research prior to buying and thought I'd be OK with winter tires. WRONG! I got stuck in 6 inches of slop in front of our mailbox and the wife and I dug for half an hour to move it 2 feet to drier pavement. I spent this weekend shopping for someone who will trade me when I'm about $5K upside down between payoff and what they are willing to give in trade. I hope to be in a different car by next weekend and write it all off as a bad decision on my part. BTW, mine is an '06 which is one of the worse. So much for saving the environment (and some gas money).

 

what was your neighbor driving and did they make it up your hill? Subaru all wheel drive versus Prius front wheel drive? You're kidding, right? Let's drag race and compare a Yugo and a Camaro. The Subaru is the champ when it comes to 4-wheel traction...their ads make you well aware that they reign supreme in that arena. If the Prius had even better tires, let us know how that works out. If no improvement and you need all-wheel drive 365 days a year, then back to Subaru you go.