Electronic Stability Control (ESC) in cars and how it works

Team Ackodrive6, Jun, 2022

Indian roads are highly unpredictable. You can expect the unexpected and need to be ready to take evasive actions. A pedestrian crossing the road out of the blue, slippery road surface, or an unexpected obstacle on the road can force you to perform sudden manoeuvres resulting in you losing control of the vehicle. That’s when the active safety features of the car come to your rescue. Electronic Stability Control (ESC) is one of those safety features. In this article, let’s throw light on ESC in cars and its working mechanism.

Electronic Stability Control (ESC) in cars

Electronic Stability Control (ESC) meaning in cars

Electronic Stability Control (ESC) is an active safety feature in cars that prevents the driver from losing control of the vehicle. ESC in cars can help prevent skidding when cornering, braking hard or performing a sudden manoeuvre. It automatically applies the brakes on individual wheels and allows the driver to stay in control of the vehicle. The system also monitors other factors such as the steering, throttle, and rotation around your car’s vertical axis to detect loss of stability.

ESC is also referred to as ESP (Electronic Stability Programme), VSA (Vehicle Stability Assist), VDC (Vehicle Dynamic Control) or DSC (Dynamic Stability Control). The names may be different, but the primary function is the same.

Electronic Stability Control working mechanism

ESC in cars comes to your rescue if you experience oversteer or understeer when cornering or making a sudden manoeuvre. The system manipulates individual wheel’s brakes and engine throttle to prevent the car from spinning out or ploughing out. The below points explain the working mechanism of this safety feature.

  • The ESC turns on as soon as you start the car, and it constantly monitors the wheel speed via wheel speed sensors and steering inputs.

  • If the sensors detect that the driver is losing control of the vehicle, the ESC activates automatically.

  • The system engages or releases the brakes of each wheel to correct the oversteer or understeer.

  • ESC enhances the brake pressure on one side of the car to steer the vehicle in that direction.

  • The system monitors the direction of skidding via the yaw control sensor. It applies the brakes on individual wheels asymmetrically so that the vehicle stays in line with the driver’s steering inputs.

  • Electronic Stability Control also works in conjunction with the traction control system to reduce the engine power if the driver applies too much throttle.

When is ESC activated?

Now you know how the Electronic Stability Control works in a car. The next question on your mind would be, in which scenarios does it jump into action? Glance through the points below to find out the answer.

  • ESC in cars activates if it detects the loss of steering control. The system constantly monitors your steering wheel inputs.

  • Suppose the car is not headed in the direction where the driver is steering. In that case, the ESC activates and corrects the vehicle's course or prevents/minimises skidding in case of emergency manoeuvres.

  • The system also activates if the driver suddenly turns the steering wheel too much in emergencies to control the vehicle. Such a manoeuvre is called over-correcting.

  • Over-correcting can happen when the vehicle oversteers/understeers due to the poorly judged corner or slippery road surface.

Pros and cons of Electronic Stability Control

Similar to any other safety feature, the ESC also has its set of advantages and disadvantages. In this section, let's look at some of the pros and cons of Electronic Stability Control.

Benefits of Electronic Stability Control

Here are the advantages of the ESC safety feature.

  • One of the most significant advantages of ESC is its efficiency. It activates automatically without any human intervention and applies the brakes on individual wheels.

  • It prevents severe accidents as it does not allow the car to skid. If the vehicle skids out of control, it may also rollover. With ESC, such incidents can be avoided.

  • It acts as a driver assistance feature in adverse driving conditions. For instance, if you are driving on a slippery road surface, stability control can help correct your driving when you lose control.

  • ESC helps you maintain control over your car even in emergencies when you try to steer hard or brake hard.

Cons of Electronic Stability Control

Below are the disadvantages of ESC.

  • Does not allow faster cornering speeds: ESC may be a critical safety feature, but when it comes to cornering performance, it doesn't help much. Since it's designed for controlled cornering, it will not help with faster cornering since it can't increase traction during spirited driving. It is one of the common electronic stability control problems.

  • Unnecessary intervention: The system can unnecessarily interfere if you attack the corners during aggressive driving in a closed environment. For example, if you take your car to a race track and try to drift, the ESC won't allow you to do it. However, some cars do come with an option of partially or completely turning off the stability control system.

  • Can lead to complacent driving behaviour: The driver may feel like pushing the car over the limits with the ESC onboard. But the safety feature may not come to your rescue if the cornering speed is too high. If you end up pushing over the limit, the car will eventually lose control.

Why is ESC so important?

Electronic Stability Control is a crucial piece of safety equipment that has made driving safer. Unexpected events on the road are a common phenomenon, but trying to avoid them while driving is a difficult task. But ESC makes it a lot easier for you to cope with such tricky situations.

For instance, if you drive on a curvy road and fail to judge the corner, the car may understeer. Ultimately, you can lose control of the vehicle. But with ESC, you will get assistance with braking and throttle management and safely correct the mistake. Hence, ESC is so important. Especially with modern cars getting faster and faster, driver assistance features such as stability control are necessary rather than luxury.

Electronic Stability Control vs traction control

ESC and Traction Control System (TCS) are often misunderstood as the same safety feature since both are related to the vehicle's stability and offer assistance to the driver. But both are different terms and have different purposes. Refer to the table below to know the key differences between ESC and traction control.

Parameters Electronic Stability Control (ESC) Traction Control System (TCS)
Purpose To prevent the loss of steering control and avoid skidding/understeer/oversteer while cornering. To prevent wheelspin during aggressive acceleration.
Category Active safety feature Active safety feature
Working mechanism The system detects loss of steering and automatically applies the brakes on individual wheels to prevent loss of control. ESC can also control the throttle if required. The system detects the wheel spin via wheel speed sensors, and the ECU will reduce the engine power to prevent loss of traction.
Driver input Not required since it activates automatically. No driver input is needed, as it engages automatically.
System override Some cars come with an override function wherein one can partially/completely switch off ESC. Generally, cars come with a traction control button to engage or disengage the system.

ESC vs AWD

AWD (All-Wheel Drive) is a popular term in the automotive industry. It is mainly associated with off-road cars. So, how is AWD different from ESC? The table below explains the difference between both systems.

Parameters Electronic Stability Control (ESC) All-Wheel Drive (AWD)
Purpose To prevent skidding or loss of steering. It can also correct understeer and oversteer during cornering. To improve traction by transmitting power to all four wheels.
Category Active safety feature Drivetrain
Working mechanism ECU detects the loss of steering/understeer/oversteer and activates ESC. It automatically applies the brakes on each wheel and controls the engine throttle, if necessary. The system transmits the power to all four wheels via a centre differential. The torque is equally split between four wheels, or it is split according to the traction required by the front and rear wheels.
Driver input No driver input needed. The system works without any driver inputs.
System override Some cars allow you to partially/completely turn off ESC. One cannot disable AWD.

ESC vs ABS

ESC and ABS (Anti-lock Braking System) are the crucial safety features in a car. Sometimes, both systems work together to avoid loss of control. The below table explains the differences between ABS and ESC.

Parameters Electronic Stability Control (ESC) Anti-lock Braking System (ABS)
Purpose It prevents the vehicle from skidding when cornering. It can also assist the driver if the vehicle oversteers or understeers. It prevents the wheels from losing traction (locking up) under hard/panic braking.
Category Active safety feature Active safety feature
Working mechanism The system detects oversteer/understeer or loss of steering and activates ESC to apply brakes on each wheel. If required, it also controls the throttle. The system detects the loss of traction during braking via wheel speed sensors. Once engaged, ABS modulates (releases and engages) the brakes to slow down/stop the vehicle safely.
Driver input Not required ABS activates if the driver applies the brakes.
System override Can partially/completely switch off ESC. One cannot disable ABS as it is a crucial piece of safety equipment.

How do ABS, TCS and ESC work together?

The ESC, TCS, and ABS are integrated systems. Hence, it is impossible to have stability control and traction control safety features without an Anti-lock Braking System. The hydraulic valve block of ABS is necessary for the traction control to prevent wheelspin. Similarly, ESC also requires wheel speed sensors and hydraulic valve block to apply the brakes on individual wheels automatically.

Top cars with ESC in India

Below is the list of cars with Electronic Stability Control in India as of March 2022.

Maruti Swift Volkswagen Polo Kia Seltos MG Astor
Tata Altroz Mahindra XUV300 Hyundai Creta MG Hector
Hyundai i20 Hyundai Venue Maruti Baleno Tata Harrier
Tata Nexon Kia Sonet Nissan Magnite Toyota Fortuner
Mahindra Thar Hyundai Alcazar Mahindra XUV700 Honda City 5th-Gen

How effective is Electronic Stability Control?

As mentioned earlier, ESC is an automated system; hence it does not require any human intervention. So, it is highly effective and efficient in operation. It will automatically apply brakes on individual wheels, and you will not even realise that system is active. Since it is electronically controlled, the reaction time is superior, and it is very efficient and reliable in emergencies. However, you cannot expect stability control to prevent an accident if you are driving over the car's limit. So, always drive within your and the car's limit.

Frequently Asked Questions (FAQs)

Let's look at some of the most common queries related to Electronic Stability Control in cars.

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What does it mean if the Electronic Stability Control light stays on while driving the car?

If the ESC light is on for an extended period while driving, it could mean a system malfunction or you have disabled the system. First, check whether you have disabled it, and switch it on. If the system is enabled and the light is on, there is a malfunction, and you must get it fixed as soon as possible.

Are ESP and ESC two different safety features?

No, Electronic Stability Program and Electronic Stability Control are the same safety features. They are different terms used by car manufacturers. The primary role and function of the system remain the same.

Is it safe to drive my car with ESC off?

It depends on your driving style and road conditions. It is safe to drive with ESC off if you are driving defensively and the road conditions are good with predictable traction. But if you drive on curvy roads with unpredictable traction, then it may not be a wise option to switch off the stability control. We recommend you not turn off the stability control when you drive as the roads are always unpredictable.

Does ESC prevent the vehicle from rolling over?

No. The stability control can only prevent the car from skidding when cornering. It can detect understeer or oversteer and assist the driver in correcting the mistake. If the vehicle spins out of control, it may roll over depending on the vehicle's speed.

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