IDLE AIR CONTROL (IAC) MOTOR - 3.9L/5.2L/5.9L ENGINES - PCM OUTPUT
The IAC motor is mounted to the back of the throttle body MAP and Throttle Position Sensor Location - 3.9L/5.2L/5.9L Engines - Typical and is controlled by the powertrain control module (PCM)

The throttle body has an air control passage that provides air for the engine at idle (the throttle plate is closed) The IAC motor pintle protrudes into the air control passage Throttle Body Air Control Passage - 3.9L/5.2L/5.9L Engines and regulates air flow through it. Based on various sensor inputs, the powertrain control module (PCM) adjusts engine idle speed by moving the IAC motor pintle in and out of the air control passage. The IAC motor is positioned when the ignition key is turned to the On position.

A (factory adjusted) set screw is used to mechanically limit the position of the throttle body throttle plate. Never attempt to adjust the engine idle speed using this screw. All idle speed functions are controlled by the PCM

 

Moderator's Note: Please disconnect the negative battery cable before performing this procedure, and do not reconnect it until you are done.

Click here to see the thread on how to clean your IAC valve/motor.