Mitsubishi Galant/Mirage/Diamante 1990-2000

Idle Air Control Motor

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OPERATION



The Idle Air Control (IAC) motor is a DC stepper motor controlled by the PCM. The IAC contains a built-in position sensor which detects the amount of opening of the motor. The position sensor outputs a pulse signal that the PCM receives and uses to adjust the motor to properly maintain the correct idle speed of the engine.

TESTING





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Fig. IAC motor testing and pin locations

Place a stethoscope (a long screwdriver works also, just place the screwdriver on the IAC and place your ear on or near the handle) on the IAC motor. Have an assistant turn the key ON with the engine OFF , and listen to the IAC motor. Several clicks should be heard as the stepper motor moves. If the clicks are heard, the driver in the PCM and the circuit are OK.

If the driver and circuits test OK, detach the connector from IAC motor. Using an ohmmeter, probe the connector on the IAC motor, NOT THE WIRING HARNESS, between pins 2 and 1 , and pins 2 and 3 . Resistance should measure between 28-33 ohms. If the resistance values are different replace the IAC motor. If the tests between pins 1 , 2 , and 3 are within specification, check the resistance between pins 5 and 4 , and pins 5 and 6 . Resistance should measure between 28-33 ohms. If the resistance values are different replace the IAC motor.

REMOVAL & INSTALLATION





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Fig. The IAC motor is usually mounted on the throttle body

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner intake hose.
  4.  
  5. Remove any necessary hoses from the IAC motor.
  6.  
  7. Detach the electrical connectors from the IAC motor.
  8.  
  9. Remove the retaining bolts and remove the IAC from the throttle body.
  10.  
  11. The installation is the reverse of removal. Replace the IAC gasket.
  12.  

 
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