All-Speed Traction Control

The traction control system is an all-speed traction control. All-speed traction control enhances mobility and prevents wheel slip when accelerating on slippery surfaces. It also provides a measure of directional stability control. Using the wheel-speed sensors, it can detect excessive yaw and help keep the car on the intended course, as for instance, when accelerating around a curve.

All-speed traction control is effective up to 85 m.p.h. (137 km/h).

The traction control system may be turned off or on by depressing the ESP OFF switch (2) located in the instrument panel switch pod (1) located in center of the instrument panel.

Traction control systems sense impending wheel spin based on a model of the rate of change of wheel speed under normal traction conditions. The all-speed traction control uses signals from the same wheel speed sensors as ABS to determine when to apply the brakes to one or more wheels and when to reduce engine torque output using the electronic throttle control to prevent wheel slip during acceleration. Throttle control makes the vehicle less reliant on brake application alone to maintain traction, increasing the operating speed range and more closely modulates speed, resulting in smoother operation. With all-speed traction control reducing engine torque as well as applying the brakes, it is possible to achieve almost seamless torque application at the wheels.

If the wheel slip is severe enough to require throttle intervention, all-speed traction control will reduce engine torque and sometimes upshift the transmission to avoid the condition. In milliseconds, all-speed traction control interrogates the engine control system to determine the current torque output, determines how much the torque output the current conditions will allow, and signals this requirement to the engine control system, which reduces the torque by partially closing the throttle. With execution of the torque reduction, the brake system reduces brake pressure to make the transition smooth, while maintaining forward progress. By reducing engine power, braking effectiveness is maintained and the system can operate throughout the normal vehicle speed range. That is why the system is identified as providing "all-speed" traction control.

The traction control system is enabled at each ignition cycle. It may be turned off by depressing the ESP OFF switch. The ESP/TCS function indicator lamp illuminates immediately upon depressing the button. Pressing this button again or turning off and restarting the vehicle will enable the traction control system.