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 air, 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.
Removal & Installation
- Disconnect the negative battery cable.
- Detach the electrical connector at the sensor.
- Remove the sensor from the throttle body.
- Install the sensor in the opening in the throttle body and tighten the sensor.
- Attach the electrical connector to the sensor.
- Connect the negative battery cable.
Checking Coil Resistance
- Disconnect the idle air control motor connector and connect the jumper (test harness).
- Measure the resistance between terminal (2) of the connector at the idle air control motor side and terminal (1) or terminal (3). Standard value: 28-33 ohms at 68°F
- Measure the resistance between terminal (5) of the connector at the idle air control motor side and terminal (6) or terminal (4). Standard value: 28-33 ohms at 68°F
- If not within specifications, replace the IAC Valve.
- If within specifications, check connectors and wiring between the sensor and ECM/PCM.
- Check that the operating sound of the stepper motor can be heard over the idle air control motor when the ignition switch is turned to the ON position (without starting the engine).
- If no operating sound can be heard, check the stepper motor drive circuit. (If the circuit is good, a defective stepper motor or engine control module is suspected.)