ETS on a Pontiac Grand Am is short for Enhanced Traction System, which is the trade name for Pontiac's electronic stability control system. All Pontiac Grand Am models from 1996 until 2003 had traction control as a standard feature, with certain trim-lines keeping traction control as an option until 2005.
In every Grand Am model in which ETS is equipped, it is activated and deactivated by the press of a button labeled "ETS" on either the dashboard or shifter. A light on the display notifies the driver when the feature is turned on or off. The ETS works differently than other electro-hydraulic traction-control systems in that it is controlled via the car's computer chip, which limits power to certain cylinders during acceleration to prevent the wheels from slipping.