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8.3L - SRT-10 The idle air control motor is mounted at the front right OPERATION 3.7L V-6/4.7L V-8 A separate IAC motor is not used with the 5.7L V-8 engine. At idle, engine speed can be increased by retracting the IAC motor pintle and allowing more air to pass through the The IAC is called a stepper motor because it is moved (rotated) in steps, or increments. Opening the IAC opens an The PCM uses the IAC motor to control idle speed (along with timing) and to reach a desired MAP during decel The IAC motor has 4 wires with 4 circuits. Two of the wires are for 12 volts and ground to supply electrical current To make the IAC go in the opposite direction, the PCM just reverses polarity on both windings. If only 1 wire is In the IAC motor system, the PCM will count every step that the motor is moved. This allows the PCM to determine When engine rpm is above idle speed, the IAC is used for the following: • Off-idle dashpot (throttle blade will close quickly but idle speed will not stop quickly) • Deceleration air flow control • A/C compressor load control (also opens the passage slightly before the compressor is engaged so that the • Power steering load control The PCM can control polarity of the circuit to control direction of the stepper motor. IAC Stepper Motor Program: The PCM is also equipped with a memory program that records the number of steps 14 - 60 FUEL INJECTION - GAS DR/DH |