Sensor Inspection

To test the motor position sensor located in the idle air control (IAC) motor, proceed as follows:

1. Connect a Scan Tool to the diagnostic connector and read the Idle Air Control Valve position.
2. With the engine at operating temperature, transmission in neutral (or PARK) and all accessories turned OFF, read the number of steps that the IAC motor is open.

Normal Value: 2-20 steps

NOTE: A new vehicle (with approx. 300 miles or less) the IAC valve position sensor may show as many as 20 steps more than normal.

3. Turn the air conditioner ON and read the number of steps that the IAC motor is open. The number of steps should increase to compensate for the extra engine load.

Normal Value: 8-50 steps

4. Turn the air conditioner OFF. The number of steps should return to the original value.
5. On vehicles with an automatic transmission, engage the brakes and place the transmission in DRIVE. Read the number of steps that the IAC motor is open. The number of steps should increase to compensate for the extra engine load.

Normal Value: 3-40 steps