What type of device is used in a typical idle air control system?

A typical idle air control (IAC) system uses a stepper motor or a solenoid as its primary device. The stepper motor adjusts the airflow into the engine's intake manifold by varying the position of a valve or pintle, allowing for precise control of the engine's idle speed. This adjustment is based on input from the vehicle's engine control unit (ECU) to maintain optimal performance and emissions under various conditions.