Electronic stability control (ESC), also called electronic stability programme (ESP) or dynamic stability control (DSC), is a computer technology that improves a vehicle's stability by detecting and reducing loss of traction (skidding). But if the sensors notice that your wheels are turned to the left, but the car is steering to the right, it knows you're skidding sideways. To help you out of it, it uses some or all of the components of the ABS and traction control systems, including wheel-specific braking and engine power reduction to bring everything back into alignment with the direction of the wheels, and get the driver back in control of the vehicle. It works when either the front or rear wheels lose traction and the vehicle begins to skid.
It continuously monitors the vehicle, in all weather conditions, and activates automatically when necessary. It can be temporarily deactivated on some models, but will re-engage by default the next time the engine is started. ESC automatically applies the brakes to each of the car's wheels, preventing the vehicle from spinning or rolling away. This technology cannot increase traction on the road, but it helps you keep your car under control during extreme manoeuvres.
If one of the wheels spins faster, which may indicate that it is on a slippery surface, the traction control system will activate the brakes on that wheel, and can also momentarily reduce engine power, helping the spinning wheel to regain its grip. Conversely, understeer can occur when the driver enters a corner while accelerating or braking, and the front wheels lose control due to reduced traction from ice, oil or other road conditions. It reduces the risk of losing control of the car when making sharp turns or emergency steering manoeuvres. That same year, the Buick Riviera introduced MaxTrac, a primitive traction control system with no brake intervention, which instead compared transmission output speed to front wheel speed to detect spin and cut engine spark until front and rear wheel speeds matched.
We cannot recommend disabling stability control completely on a public road, but exceptional drivers who want to fully explore the limits of their performance vehicle on a closed road or circuit may find the disabled setting valuable. Stability control is a safety system, so its operation is continuously monitored by the on-board diagnostic electronics. However, be aware that the esc light may be an indicator that you are driving on a slippery road, and you may need to reduce speed to improve your control. If they don't match, the system applies the individual wheel brakes (as well as the engine controls, if necessary) to align the vehicle's path with the driver's intention.
The system is highly effective, and Transport Canada studies suggest a 29% reduction in crashes caused by driver loss of control as a result. Stability control uses components and sensors from other vehicle safety features, such as anti-lock brakes (ABS). Off-road oriented vehicles that offer different terrain modes adapt the level of stability control intervention in each mode to suit different terrains, so it is best to set this mode to suit the terrain to be driven over. Modern stability control systems take advantage of all the hardware required by traction control and anti-lock braking systems (a brake pedal application sensor and wheel speed sensors at each wheel, plus a hydraulic valve body capable of independently relieving or adding pressure to the brake circuit for each wheel) and adds several new sensors.
In addition, the ESC features a control unit that tracks the angle of the car's steering wheel, along with rotation around the vehicle's vertical axis.
