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What is Traction Control?

Posted by Auto.com Staff | Jan 3, 2019

Traction control is known by many names such as Electronic Stability Control (ESC), Dynamic Stability Control, or simply Traction Control System. It is a safety-oriented system that seeks to control engine output and/or transfer engine power output to whichever wheel has the best traction in order to reduce traction loss and provide a stable and predictable driving experience in all types of weather conditions.

Traction control is often used in conjunction with the antilock brake system (ABS) and utilizes wheel speed sensors to determine if one wheel is moving faster than the others. This type of wheel-spin would be the case if one or more tires were spinning in icy or otherwise slippery conditions. Different traction control systems have different ways of controlling power delivery, but a common method is to employ the anti-lock brakes in order to slow down the slipping tire.

The differential plays an integral role in how traction control works. For those that may not know: the differential is what splits the power between two wheels on a single axle, or between front and rear axles of an all-wheel-drive (AWD) vehicle. Although they vary in design, all differentials must allow the wheels to spin at different speeds so that the vehicle can drive around corners and such. With the brake applied to the one side, the differential will then readjust the bias and channel that power to another wheel.

In the case of an AWD system, the traction control mechanism may also channel the power to a different axle through the center differential. Other inputs such as from a steering angle sensor can provide data regarding the driver’s intent and further improve handling by transferring power to a front or rear wheel. The power goes where it is deemed most essential.

These systems are an evolution above and beyond the mechanical limited slip differentials of the old days. They often have much more sophisticated and complex programming and can reduce the tendency of rollover crashes in taller vehicles with a higher center of gravity. Beginning in 2012, federal law requires that all new vehicles sold in the United States must come equipped with traction control as a standard safety feature. While traction control cannot account for driver error, it can make driving safer, especially in uncertain conditions where improved vehicle control is essential.