1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Traction Control feature

Discussion in 'Prime Technical Discussion' started by EdTechGuy, Feb 22, 2021.

  1. EdTechGuy

    EdTechGuy New Member

    Joined:
    Aug 7, 2020
    10
    13
    0
    Location:
    Missouri
    Vehicle:
    2020 Prius Prime
    Model:
    LE
    This is my first winter with my 2020 Prius Prime, and I finally found a reason to use the Traction Control button. I found that while climbing the icy hill in the alley leading to my garage, my Prime brakes were pulsing crazily and the car wouldn't climb the hill. I found that hitting the "TRAC" button let me spin my way up, as all my past cars have been able to do. Great! And there's no way to forget it's off, since the on-screen message overrides my other info display.

    The manual makes it sound like Traction Control interacts with other systems and generally shouldn't be used. Has anyone found other scenarios where turning off Traction Control is helpful?
     
  2. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,831
    1,825
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    One of my very few complaints about my Prii (I'm on my third one) was the so-called "traction Control". In the early days (my 2004), it was actually there to protect the drive train from sudden, high torque, events (a spinning wheel hitting a patch of dry pavement) and breaking something. There were much better solutions to that problem than shutting down the drive train when a wheel slip occurred. There is already a torque limiting clutch between the engine and the HSD that deals with excess torque at that point in the drive train. Two more of those clutches, one in each half shaft, would protect the system and not leave me vulnerable to being broad sided when the Prius stops while accelerating into traffic and a bit of slippage occurs due to sand on the road.

    My new 2020 AWDe Prius does not exhibit this issue due to the extra traction from the rear wheels so all is good now.

    JeffD
     
  3. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,072
    14,976
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    The first-gen Prius (2001-2003) did indeed have a "traction control" that could not do anything but limit power, and was really only there to prevent the magnets in MG1's rotor taking an unscheduled departure from the car.

    With Gen 2 (2004 on), there was a traction control like those in other cars, where it can detect if a particular wheel is slipping and selectively apply the friction brake on that wheel, keeping more power available to the wheel that isn't slipping.
     
  4. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,831
    1,825
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    My experience with my 2004 was that the brakes were not involved (my 04 just stopped). This may have been introduced with the 2006 update to the design, but I never looked into it.

    JeffD
     
  5. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,072
    14,976
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    See page TH-47 of the 2004 New Car Features manual.

    [​IMG]
     
  6. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,474
    38,105
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Snow tires? They’ll help a lot too.
     
    Ovation likes this.
  7. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,831
    1,825
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    Note that it says "if one of the wheels", when both spun my 04 Prius just shut down the engine(s) so getting up my driveway was sometimes a challenge. The problem was greatly improved when I replaced the OE tires after a few years first with Michelin MXV4+ and then later with Nokian WRs.

    JeffD
     
    Mendel Leisk likes this.
  8. m8547

    m8547 Senior Member

    Joined:
    Aug 8, 2018
    927
    615
    0
    Location:
    Colorado
    Vehicle:
    2018 Prius Prime
    Model:
    Prime Plus
    In my experience the traction control on the Prime could use some fine tuning. If one of the wheels loses traction it should pulse the brakes to that wheel so that the wheel with grip also has torque. Sometimes it works, but sometimes it allows excessive wheel spin which is counterproductive and risks damaging the drivetrain if the spinning wheel suddenly gets traction. It seems to work OK once the car is moving, but from a stop or especially if the steering wheel is turned it often allows excessive wheel spin. I mostly drive in EV mode, so I don't have much experience with how it behaves in HV mode. Turning traction control off should allow as much wheel spin as you want, but I can't see how that would help in most situations.

    I also have a Toyota 4Runner, and it's ability to use the brakes to transfer power is incredible. It works almost as well as a locking differential. I can crawl up obstacles off road with one or two wheels in the air. So Toyota is capable of programming a system that makes good use of available traction.
     
    E-GINO likes this.
  9. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,072
    14,976
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Naturally, if there are only two driving wheels and more than one is spinning, that'll be a challenge for even the cleverest traction control. If that's happening routinely, the real solution is going to be to make the traction better, as with better winter tires.

    Indeed. It will pretty much always be more effective to try to look like one of these guys




    than to polish the ice like this guy

     
    davecook89t likes this.
  10. davecook89t

    davecook89t Senior Member

    Joined:
    May 10, 2016
    1,057
    789
    0
    Location:
    Washington State, Florida
    Vehicle:
    2017 Prius
    Model:
    Four Touring
    That last video makes you want to shift quickly from D to R, as if it was a manual transmission. That's what I did with our 2004 Sable, and had to replace the transmission shortly thereafter.
     
  11. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,831
    1,825
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    The ford auto tranny in that era was very unreliable. Almost all of them failed just out of warranty. your Sable tranny failure may not have been your fault.
     
    davecook89t likes this.
  12. davecook89t

    davecook89t Senior Member

    Joined:
    May 10, 2016
    1,057
    789
    0
    Location:
    Washington State, Florida
    Vehicle:
    2017 Prius
    Model:
    Four Touring
    I didn't think it was a coincidence. I did get out of the snow (I guess doing what I did caused it to rock back and forth a little bit, which is what I was trying to accomplish), but it failed a month or 2 later. It was the wife's car, I accepted blame for it, but it was just another failure in a long line of failures on that car.
     
  13. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,072
    14,976
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Not guaranteed to be innocuous in a manual either. I had about 20 minutes of rocking once to get a manual transmission truck out of a plowed-in position. Nothing failed, but the clutch left a strong scent of 'foundry' all up and down the block. (I once lived not far from some foundries; it was that smell.)
     
    davecook89t likes this.
  14. pghyndman

    pghyndman Active Member

    Joined:
    Dec 27, 2018
    498
    463
    0
    Location:
    CT shoreline
    Vehicle:
    2021 Prius Prime
    Model:
    Limited
    It's been many years, but I recall lightly apply the parking brake to limit wheel spin. I may be wrong, but he lurching seen in the above videos seem to indicate too much throttle is being applied and the car is trying its best achieve traction (ie: spinning too fast = less traction). A case of steady, slow, and easy controls the day, not ooh, ooh, ooh... I'm slipping, better give it more throttle!
     
    davecook89t likes this.
  15. m8547

    m8547 Senior Member

    Joined:
    Aug 8, 2018
    927
    615
    0
    Location:
    Colorado
    Vehicle:
    2018 Prius Prime
    Model:
    Prime Plus
    The parking brake only works on the rear wheels, so unfortunately the parking brake trick won't work on these FWD cars.

    Most people give it way too much gas when the wheels start to slip, then complain about the traction control system cutting power.
     
    douglasjre likes this.
  16. Ovation

    Ovation Active Member

    Joined:
    May 11, 2021
    156
    129
    0
    Location:
    Quebec
    Vehicle:
    2021 Prius Prime
    Model:
    Base
    In slippery conditions, my driver's ed teacher from long ago (early 80s) had it exactly right--imagine a fresh egg between your foot and the accelerator and whatever you do, DON'T crush it. Very sound advice that I've followed in New England, and later, Quebec winters. That and winter tires, of course (no choice in Quebec--required by law from 1 December to 15 March).
     
  17. PaulDM

    PaulDM Active Member

    Joined:
    Sep 24, 2016
    616
    317
    2
    Location:
    UK
    Vehicle:
    2022 Prius
    Model:
    Excel
    Stick it in economy mode under slippery conditions
     
    douglasjre likes this.