Traction Control (TRAC)

There is no solid information. When asked about it, Toyota said that integration between systems has been improved, and the the new traction control allows for some wheel spin. However, the current traction control also allows for wheel spin, so it's hard to say what that means.

Tom

 

there was huge improvement between trac/vsc/abs in 2003 and 2009 Corolla, and i expect the same for Prius... 2nd gen used older/slower system at the time, all newer Toyota got better systems, some are now 2 generations more advanced.

 

Perhaps Toyota will let the new Prius brake each front wheel individually so that *both* front tires have to lose traction before the car becomes immobile (a limited slip differential achieves the same goal in a different way). It's been stated here that the current TRAC can't do that, which I've never understood since the underlying technology to sense individual wheel slippage and brake individual wheels is already present in the ABS and VSC systems. Wouldn't the ability to brake a slipping wheel individually greatly reduce the chance of getting stopped or stuck as reported here by some owners?

 

Yes, it would be a great improvement.

Tom

 

But does the current TRAC brake an *individual* front wheel that's lost traction, thereby allowing the other one to drive the car if it has any traction? My understanding was that TRAC doesn't do that and that, if it did, the car would be far more capable in low-traction conditions.

 

The rated 2010 MG torque output is around half of 2G. Also, the three 2010 vehicles on display at PCD seemed to have better tires than Goodyear Integrity. Maybe the reduced available torque at low speeds will help the traction control system to behave more gracefully in low-traction situations. We'll see next winter.

 

My understanding and experience suggests no individual braking with the Gen II. This information is the first that I have heard about it. I wonder if it is in error?

Tom

 

Based on my personal experience, the Prius does NOT apply a brake to a spinning wheel. It just reduces torque, sometimes to zero.

If the Prius applied a brake to a spinning front wheel, that would have solved 90% of my traction woes. Around here, it's quite common to find intersections where the curbside is icy, but the center of the lane is bare.

In such a situation, on "all season" tires, my Prius becomes helpless and will just sit there. With aggressive studded tires, no problems.

My FJ does apply the brake to a spinning wheel, so I'm very familiar with how it sounds and feels. The FJ also has an electric brake boost system, and in the above situation at the intersection, when the light turns green the brake boost pump makes a buzzing sound, and I smoothly drive away

Note the stick shift FJ is full time 4wd. I have an auto trans, so it's part time. If you shift an auto trans FJ into 4H, you disengage the VSC, so I never operate in this mode on the street or on public roads

In theory, if the vehicle traction control applies the brake to the spinning wheel, that vehicle could easily climb a moderate grade with one side glare ice, and the other side bare. I have found parking ramps at malls here that are just like that, one side glare ice and the other side bare, due to how the sun falls on the ramp

With my Prius, it can have problems even with the studded tires, if I come to a stop on the ramp (Traffic ahead and cars backed up). With the FJ, no problem at all, but the brake boost pump is constantly buzzing as it climbs the grade

 

I wonder if it would be best for a 2010 Prius driver to switch to EV Mode if s/he were to encounter a situation encountered in the past most frequently by 2004-2005 Prius drivers, i.e., power is cut off while going up a slippery incline.