The Idle Air Control (IAC) valve controls the engine idle speed and dashpot functions. The valve is located on the side of the throttle body. This valve allows the necessary amount of air, as determined by the Powertrain Control Module (PCM) and controlled by a duty cycle signal, to bypass the throttle plate in order to maintain the proper idle speed.
Turn the ignition switch to the OFF position. Disengage the wiring harness connector from the IAC valve . Using an ohmmeter, measure the resistance between the terminals of the valve. NOTE: Due to the diode in the solenoid, place the ohmmeter positive lead on the VPWR terminal and the negative lead on the ISC terminal. If the resistance is not 7–13 ohms, replace the IAC valve.