Traction Control System
Traction Control was developed in Formula One racing to control wheel spin as cars travelled through turns and on slick surfaces (oil) allowing consistent application of power and maintenance of control. The VSC system orchestrates the ABS and Active Traction Control (A-TRAC) sensors,actuators and computor electronics.
If a wheel loses traction, the computer will help minimize wheel slippage by controlling engine output and brake fluid pressure that is applied to the slipping wheel. Other system maintain control by Clamping down on the fuel supply to the engine (throttle), lowering engine power.
Typically the ABS is used to slow one spinning drive wheel, which sends power to the other as a limited-slip differential would. Then the engine power limiters kick in only if both drive wheels are spinning faster than the passive wheels, which indicates that both drive wheels have lost traction. Because the wheel-rotation sensors are part of any antilock braking system, cars equipped with traction control always have antilock brakes as well.
Traction control is like ABS for acceleration. If a wheel starts to spin, traction control may cut engine power or pulse the brakeon the spinning wheel (or perform both operations) to help transfer some of the engine's torque across the axle to the wheel with more grip. Expert off-road drivers sometimes pump the brake pedals on vehicles without traction control to try to accomplish the same thing.
4-ETS (four-wheel Electronic Traction System):
Working with the vehicles'full-time four-wheel drive, 4-ETS uses individual wheel-speed sensors to detect the onset of wheel slip. Then it individually brakes the slipping wheels as needed, providing the effect of locking the front, center and/or rear differentials. The 4-ETS system continually balances the torque split to direct power to the wheel or wheels with traction.