NOTE: This procedure is only for 2.4L engines
The Idle Speed Control Motor (ISCM) position sensor is located at the mouth of the intake manifold plenum, near the TPS. The ISCM position sensor converts the position of the plunger in the ISCM to a voltage, which it then inputs to the ECM. The ECM takes the signal and controls the ISCM.
If the plunger in the ISCM moves from the contracted to the extended position, the resistance between the variable resistor terminal and the ground terminal of the ISCM position sensor increases in proportion to the amount of extension. Thus the voltage at the variable resistor terminal of the ISCM position sensor increases as the plunger is extended.
The ISCM position sensor is the most important sensor in control of the idle speed. In many cases where failures occur due to changes in the engine load, as when the air conditioning switch is turned on while the engine is idling, the fault lies with this sensor.
If the output voltage of the ISCM position sensor deviates from the standard value even though the results of the checks of the ISCM position sensor wire harness and individual components are normal, the problems may be that the basic idle speed adjustment is faulty, there are deposits on the throttle valve, air is being sucked into the intake manifold through gaps in a gasket, the EGR valve seat is sealed poorly, or the combustion in the cylinders is poor (spark plugs, ignition coil, injectors, compression pressure, etc.).