How Does Subaru's Traction Control Work? | Traction Control is part of Subaru's Vehicle Dynamics Control System | Traction Control Light
How Does Traction Control Work?
Traction Control, Electronic Stability, Limited-Slip Device, Anti-Lock Braking System (ABS), Electronic Brake Force Distribution (EBD), and Brake Assist are all components of the Vehicle Dynamics Control System (VDC).
Here is a great explanation from C.J.Spitz of
"The components of the VDC system are:

Direction: uses brakes to slow down wheels to reduce spin and help control vehicle direction.
Skidding: yaw and steering wheel sensors use brakes to slow down spinning wheels and re-direct power to the wheel(s) with the best traction to re-gain control.
Engine power: controls engine output to slow spinning by reducing spark to cylinders to cut back power and help re-gain control."


Many of the sensors in your Subaru were originally developed for the aerospace industry.  These sensors allow the VDC system to know exactly where you want your car to go and where it's actually going.  VDC makes sure those two places are the same!
In three words, VDC prevents skids.  When you're driving around a curve, you know where you want your car to go. Your Subaru does, too, because it has a host of sensors that monitor where your car is and where you're pointing it.  If your wheels start to move laterally, sending your car for the ditch, VDC will apply engine power or the brakes to speed up or slow down individual wheels, pulling your car back into your intended line through the curve.  First introduced as an option in 2001, it has been standard on every Subaru since 2009.  
Traction control is automatically "ON" every time you start your vehicle. Although there are many benefits and safety aspects of keeping Traction Control on, there are a few instances where you may want to turn the Traction Control off:  Mother nature just delivered 24 inches of snow and then the giant municipal snowplow deposited a 4 foot pile of it across the end of your driveway, just before you are due to be at work. Fun times. So, instead of waiting for the plow guy to get to your driveway in the afternoon, you're going to drive through that snowbank. Yes you. Do you drive a Subaru, or don't you? Start that Subaru, turn on those heated seats, buckle up and shut the traction control off. Today you're living the dream of every Subaru...and getting to work on time. Here's a photo showing the location of the Traction Control switch in a 2014 Subaru Forester:
Of course there are other instances where you'd want to turn the traction control off, but we can't advocate for doing donuts, street racing, or hosting your own rally cross. If you search NASIOC or other Subaru forums, you can read all about instances where you'd want to turn the traction control off. 
Don't worry-- if you've turned the Traction Control off, the system automatically resets itself the next time you start your engine. Again, Subaru is looking out for your safety and best interest.
How Does Vehicle Dynamics Control Work?

VDC incorporates a host of different technologies to prevent skids and accidents.  Throw some vegetable broth in there and you'll have alphabet soup.  

  • Electronic Stability Control (ESC): In situations such as a vehicle losing control due to unexpected understeer or oversteer, individual brakes are applied, engine power is reduced and torque distribution is shifted to regain vehicle stability, therefore aiding driver control.
  • Traction Control System (TCS): Reduces engine power to minimize wheel slip.
  • TCS Limited Slip Device (LSD): Transfers power from the wheels that slip to the wheels that grip to help maintain traction and control.
  • Anti-lock Braking System (ABS): Providing significant driver assistance in minimizing stopping distance and maintaining vehicle control under brakes. ABS maintains control to enable the driver to steer around obstacles and reduce stopping distances.
  • Electronic Brakeforce Distribution (EBD): Is the electronic control of braking pressure to the front and rear wheels all the time.
  • Brake Assist: Is a driver assistance system that works to minimize stopping distances in emergency situations by ensuring stopping power is maximized.
 Here is a short video on Power and Traction

Learn more about Vehicle Dynamics Control and Traction Control here.


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Categories: Technical Schmecnical