The purpose of the Idle Control System is to manage the engine idle speed. This is often controlled by an Idle Air Control Motor mounted on or near the Throttle Body of the Intake Manifold. In some cases, an Idle Air Stepper Valve or Motor is used. To raise or lower the engine Idle speed, the Powertrain Control Module (PCM) opens or closes either of these devices to allow more or less air by the Throttle Plate in the Throttle Body. This is done in order to meet the ever-changing loads placed on the engine, such as the use of air conditioning, heat, and wipers.