The Stanley Subaru Scoop



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 Cars101.com:

"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.


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.




Have more questions? Need to know how other stuff works? Check out the Technical Schmecnical tag or try our FAQ.
Categories: Technical Schmecnical

Comments

JERRY
I have a 2009 Subaru Forester. Does the fact that the "traction control" light is constantly on indicate a safety issue? I have had a Subaru dealer check the vehicle and they've stated that the traction control, ABS etc. are all physically working properly. At this point, they have suggested that it is merely an electrical problem and, as a result, to locate that problem they would have to open up the dash to check for the electrical problem.
Comments please.
Post Follow Up
Spencer Patterson King
Hi, Jerry,

If the light is still on, it needs diagnosed. Since your local dealer has already looked at your Forester and has assessed it, we would defer to their judgment about the risk and your needs.
Post Follow Up
zinol
today I started my 2011Subaru impreza around 12 noon. A minute after I was driving the car started to idle roughly. I noticed the check engine light came on along with the VDC indicator. After 10 seconds both lights came off. About 2 minutes after it occur again for 5 seconds. I continued to drive and it did not reoccur. We had a lot of rainfall recently and the car was parked in the driveway.. Could it be that the sensor for the VDC was damp? Where exactly is that sensor located? Thank you
Post Follow Up
Spencer Patterson King
Your check engine light and your VDC light probably came on because you had a rough idle. There isn't just one VDC sensor, it's tied to many systems to monitor how your vehicle is performing, and if you had a rough idle, that could affect it. There could be a couple reasons for the rough idle. In order to be sure, we'd have to take a look at it. You can call us at 207-667-4641 or schedule an appointment at https://www.stanleysubaru.com/service/appointment.htm
Post Follow Up
chuck knight
71 year old man, lots of driving experiences. first time in rain with new Subaru forester, driving 65mph and experiencing some problems. each time I went thru a wet spot the car acted like the wind was blowing me sideways, slightly. stopped and checked the tires, all were fine. within a few miles on a straight freeway, I was jerked to the left and smashed into the divider. there was no warning!, just a severe left turn and covered 20 foot meridian in about 1/2-2/3 second. could not control steering, or so it seemed. I was probably on cruise control at about 65mph. could wheel spin and the applied breaks by the traction control caused the accident? chuck
Spencer Patterson King
Hi, Chuck,

We are really sorry to hear about your collision. As for the cause, that's really something the police and your insurance would need to determine. You were probably given a report number at the scene, and I would suggest following up with that to find out what happened.

Traction control is designed to keep your vehicle going the direction it's pointed and has been pretty rigorously tested.

We hope you are well and wish you the best.
pamela
I live in the mountains of Tennessee. I bought my Subaru Tribeca new in 2013 and love it. I have a very steep incline getting out of my driveway. When it snows there are times that I just cannot get out. I feel that I am doing something wrong with my car. I have owned other all wheel and 4 wheel drives before and sometimes albe and sometimes not able to get out. Should I be turning the non skid sensor off before climbing the (snow covered) embankment?
Spencer Patterson King
Hi, Pamela,

It is possible to turn off the traction control so the wheels spin to get you moving, but it does disable a lot of the features of the Symmetrical All-Wheel Drive.

What we would recommend instead is making sure you have a good snow tire. Snow tires are made to work in freezing temperatures and have a number of features that give them better traction in situations like yours. A good snow tire will work wonders. Snow tires, studded tires, or a traction device are certainly worth looking into.

Best of luck!
Louis Mettey
Thank you for this very good explanation. The manual creates more questions than it answers.
Post a Comment
true
true true true true true true true true true true true true
; ;