Stability control is known by various names through out the automotive industry, this is a very important feature
on any vehicle that has it. Stability Control uses the same systems as
traction control and ABS and other sensors such as
yaw rate to detect and correct a possible slide, usually a slide in a sideways direction that may
occur when you're trying to steer around obstacles at a relatively high speed.
The blue represents a car with stability control and the other image is the control in a BMW vehicle
(images from www.bmw.com)
Have you ever noticed how people and things can slide on the seats when turning or
braking at certain speeds.
That's because there is a transfer of weight and this sudden weight transfer can cause the vehicle to skid or even
overturn. How Stability Control works is best explained with an example.
Imagine you're driving along an open country road about 60 mph with a pick up
in front of your vehicle and something falls from the tray and into your path. Your immediate reaction is to
steer away from the obstacle to avoid hitting it and then steer back into your regular path.
At 60 mph this task will not be as easy as I just made it sound. At the high speed you may pull too hard on
the steering (for the example we'll imagine you steer to the left) and your vehicle may
understeer. Sensors on the vehicle will sense this and and send this info to an
ECU which would apply the brakes to the inside front wheel which would be the left wheel in this case. This action
will give the right wheel an advantage and force the vehicle to turn closer to your intended direction.
After avoiding the obstacle and attempting to get back into your lane your vehicle may now attempt to
oversteer as there will be a great weight transfer from right to left causing the vehicle to angle further right
than you intended. The ECU will then use the brakes to reduce the rotation of the outside tires which will be the
left again to correct the oversteer and prevent the vehicle from spinning
out of control.
All stability control systems will not react in exactly the same way as I just stated in my example but it is
a general indication of the functionality. The scenario may not play out exactly as stated but the system will correct
anything contrary that it detects.
These systems along with traction control can be turned off or have various settings in many vehicles and
you should learn the controls. Some of the names of this feature known to the industry are Electronic Stability Program
(ESP), Dynamic Stability Control (DSC), Dynamic Stability Traction Control (DTSC), Active Handling System and Vehicle
Skid Control (VSC).
I think now is a good time for me to say that Stability Control reduces the possibility of a skid,
under and oversteering. Don't try to make a 90 degree corner while driving at 90 mph and expect the system to