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What Does Stability Control Mean in My Car?

stability control in a carYour car’s electronic stability control (ESC) goes by a variety of names depending on what make of vehicle you drive. In some vehicles, it’s called a Vehicle Dynamic Control (VDC). In others, it’s called a Dynamic Stability Control (DSC). And lastly, some are called a Vehicle Stability Control (VSC).

Whatever its name, the ESC is your car’s computer system that detects when you begin to skid and automatically applies the brakes to one or more wheels individually to help you steer in the correct direction.

How It Works

Your ESC constantly works to compare your steering wheel angle to the actual direction in which the car is going and each wheel’s road speed. If it detects lateral slip in your tires, it adjusts the brakes, throttle differential and/or suspension to bring your car back into line.

One of the best things about your ESC is that it works on wet or icy pavements as well as dry ones. Since it detects a skid much more quickly than you do, it may correct it without your even knowing that you were starting to skid. You’ll know it happened because most ESCs either flash a dashboard light or emit a beep.

What It’s Not

ESCs do not enhance performance and are not a replacement for your own safe driving practices. If you’re forced into a severe steering correction to avoid a deer that darts into the road in front of you, such a violent maneuver may well exceed the limits of your ESC. Should you encounter an extreme hydroplaning situation, your ESC will not be able to help you if the wheel(s) it uses for braking is/are not actually touching the pavement. Additionally, an ESC doesn’t increase traction or allow you to corner faster.

ESC Components

An ESC’s brain is its electronic control unit (ECU) that also may control other vehicle systems such as the anti-lock braking system, traction control system, and climate control system. The ESC has at least four sensors:

  • Steering wheel angle sensor that determines where you want to steer,
  • Yaw rate sensor that measures how much the car is actually turning,
  • Lateral acceleration sensor that measures how fast the car is moving sideways, and
  • Wheel speed sensor that measures how fast your wheels are spinning.

Some ESC systems also have a longitudinal acceleration sensor that gives information about road pitch and a roll rate sensor that improves error corrections provided by the four main sensors.

The ESC is always on by default, but some systems have an override switch so you can disable it if you’re stuck in heavy mud or snow or driving on a “donut” spare in an emergency. However, the next time you start your car the ESC is activated once again.

Safety Test Results

Although stability control systems first started appearing in the 1980s, they didn’t become widely available until the mid-90s. Even then they often were after-market products. The National Highway Traffic Safety Administration (NHTSA) has required that all new passenger vehicles sold in the United States as of the 2012 model year be equipped with ESCs.

The NHSTA concluded as far back as 2004 that ESCs reduce car crashes by 35 percent and SUV crashes by 67 percent. The Insurance Institute for Highway Safety (IIHS) issued its own study two years later, finding that ESCs reduce the likelihood of a fatal car crash by 43 percent. A vehicle now must have an ESC at least as an available option in order to qualify for the Top Safety Pick award.