Traction Control vs. Stability Control Systems: What Is the Difference?


Source: Motor Trend posted this piece by Engineering Editor Frank Markus presenting a comparison, including historical perspective, between traction control and stability control systems, both today utilizing brake-system electronics to function. Here is an excerpt of the story which can be viewed in its entirety by clicking HERE.

The difference between traction control and stability control is like the difference between a GED and a master’s degree or PhD in vehicle safety. Stability control is just traction control with more vehicular education (computer programming) and better tools (a more powerful processor and more electronic sensors).

Clearly the anti-lock brake system, or ABS as we now know it, came first—on the 1971 Imperial. That same year, the Buick Riviera introduced MaxTrac, a primitive traction control system with no brake intervention, which instead compared transmission output speed with front wheel speed to detect spin and cut engine spark until the front and rear wheel speeds equalized. With no way to reduce fuel flowing through the carburetor, this reportedly led to some impressive backfires.

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Stability control sort of debuted on the 1990 Japan-market Mitsubishi Diamante, variously referred to as active trace and traction control, then Active Skid and Traction Control (ASTC), but America’s first taste of a system like the ones we know today arrived with help from Bosch on the 1995 Mercedes-Benz S600 coupe. Let’s examine and compare the systems as they exist today.

What Is Traction Control?

This active safety feature was engineered to allow vehicles to make optimal use of the accelerative traction available on any given surface by measuring wheelspin, and then controlling it by using the anti-lock-braking system’s hydraulic solenoids to apply braking pressure and/or by employing the engine’s electronic throttle, fuel, or spark controls to trim power and slow a spinning wheel. These systems frequently offer the option of being switched off. The button to do this might be marked TC, TCL, or with an icon depicting the rear of a car above two backwards-S-shaped burnout marks. If your vehicle is equipped with both traction and stability control, they will almost certainly be controlled by the same button, which may then be labeled ESC, VSC, or with the icon. For a complete list of traction and stability control acronyms, scroll to the bottom of this article.

What Is Stability Control?

Modern stability control systems leverage all the hardware required by the traction control and anti-lock brake systems (a brake-pedal application sensor and wheel speed sensors at every wheel, plus a hydraulic valve body able to relieve or add pressure to the brake circuit for each wheel independently) and adds several new sensors. A steering wheel position sensor joins the brake and accelerator-pedal sensors to inform the system of the driver’s intended path and speed. A yaw sensor measures how much the vehicle is rotating around its vertical axis (what you experience as a skid or spin), and a three-axis accelerometer module detects both lateral and longitudinal acceleration, as well as any angular slope the vehicle is driving on. Consulting all these sensors, a more powerful computer then compares the vehicle’s actual motion with the driver’s intention. If the two don’t match, the system applies individual wheel brakes (as well as engine controls, if necessary) to bring the vehicle’s path into alignment with the driver’s intention. Note that because stability control became mandatory in the U.S. in 2012, all new passenger vehicles are equipped with the holy trinity of driver-assist systems: ABS, traction, and stability control.

The entire post can be viewed by clicking HERE.

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