The amount of air taken in during idling is regulated by the opening and closing of the servo valve located in the air passage that bypasses the throttle valve. The servo valve is opened or closed by the activation of the stepper motor (incorporated within the idle air control motor in the forward or reverse direction. Battery positive voltage is supplied, by way of the MFI relay, to the coil of the stepper motor. The engine control module switches ON the power transistors (located within the engine control module) in sequential order, and, when current flows to the stepper motor coil, the stepper motor is activated in the forward or reverse direction.
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.)