ESC compares the driver's intended direction in steering and braking inputs, to the vehicle's response, via lateral acceleration, rotation (yaw) and individual wheel speeds. ESC then brakes individual front or rear wheels and/or reduces excess engine power as needed to help correct understeer (plowing) or oversteer (fishtailing). ESC also integrates all-speed traction control, which senses drive-wheel slip under acceleration and individually brakes the slipping wheel or wheels, and/or reduces excess engine power, until control is regained. ESC cannot override a car's physical limits. If a driver pushes the possibilities of the car's chassis and ESC too far, ESC cannot prevent a crash. It is a tool to help the driver maintain control.

ESC combines anti-lock brakes, traction control and yaw control (yaw is spin around the vertical axis).



Traction control is not just used for moving a vehicle from stationary without slippage. During hard maneuvers in a front wheel drive car there is a point where the wheels cannot both steer and drive the car at the same time without losing traction. With traction control, it's less likely for this loss of control to occur. There is a limit though, when the tires lose grip. The car will not corner as sharply as indicated by the front wheels, this is Understeer. In some front wheel drive cars, Traction Control can induce Lift-off oversteer due to its throttle retarding capabilities. This can keep some cars stable in long maneuvers.
 
now to me from my above post my interpretation of that is that is is the esp that cases the back ind to kick out as it attempts to continueally attempt to correct the cange in direction caused by heavy braking.

there fore i agree that the esp is never switched if where as the tc is what is actually sitched of to allow you to accelerate better