See Figure 1
The Idle Air Control (IAC) motor, attached to the side of the throttle body, is operated by the PCM. The PCM adjusts engine idle speed through the idle air control motor to compensate for load on the engine, or changes in coolant temperature or barometric pressure.
The throttle body has an air passage that provides air for the engine during closed throttle idle. The idle air control motor pintle protrudes into the air bypass passage and regulates the air flow through it. The PCM adjusts the idle speed by moving the IAC motor pintle in and out of the bypass passage. The speed is based on various sensor and switch inputs received by the PCM.
Visually check the connector, making sure it is properly attached and all of the terminals are straight, tight and free of corrosion.
You need to have access to a DRB® or equivalent scan tool to accurately test the Idle Air Control (IAC) motor and related circuits. Make sure to carefully follow all of the scan tool manufacturers directions when testing the IAC motor.
If you do not have access to a scan tool, this simple test should give you an indication if the circuit is working properly:
- First attach a tachometer to the engine, then start the engine.
- Observe the idle speed. Pull a vacuum hose (like the one leading from the brake booster to the intake manifold). The idle speed should rise, then fall as the IAC motor tries to compensate for the vacuum leak.
- Reattach the vacuum hose. The idle should drop, then stabilize.
- If the engine reacted as indicated, the circuit is probably OK.
REMOVAL & INSTALLATION
See Figures 2 and 3
You will need to have access to a DRB® or equivalent scan tool when installing the IAC motor, as the IAC motor pintle must be properly retracted if it is more than 1 in. (3mm).
- Disconnect the negative battery cable.
- Disconnect the EVAP purge hose from the throttle body.
- Remove the throttle body from the vehicle, as outlined in Fuel System of this guide.
- Detach the electrical connectors from the IAC motor and Throttle Position (TP) sensor.
- Unfasten the IAC motor mounting screws from the throttle body, then remove the motor from the throttle body. Make sure the O-ring is removed with the motor. Remove and discard the O-ring.
When servicing throttle body components, always install the components with new O-rings and seals, when applicable. Do NOT use any lubricants on the O-rings or seals, as damage may result. If you're having trouble, use a little water to help ease installation.
- The new IAC motor has a new O-ring installed on it. Measure the pintle on the new IAC valve. If it is longer than 1 in. (3mm), it must be retracted using the Idle Air control Motor Open/Close test on the DRB® or equivalent scan tool. Note that the battery must be connected for this test.
- If the old IAC motor is being installed, place a new O-ring on the motor.
- Carefully plate the IAC motor into the throttle body and install the retaining screws. Tighten the screws to 17 inch lbs. (2 Nm).
- Attach the electrical connectors to the IAC motor and TP sensor.
- Install the throttle body. Connect the EVAP purge hose to the throttle body nipple.
- Connect the negative battery cable.