Chrysler Caravan/Voyager/Town and Country 1996-1999

Idle Air Control (IAC) Motor

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OPERATION



See Figures 1, 2 and 3



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Fig. Fig. 1: The Idle Air Control (IAC) motor and Throttle Position Sensor (TPS) location on the throttle body-2.4L engine



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Fig. Fig. 2: The Idle Air Control (IAC) motor and Throttle Position Sensor (TPS) location on the throttle body-3.0L engine



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Fig. Fig. 3: The Idle Air Control (IAC) motor and Throttle Position Sensor (TPS) location on the throttle body-3.3L and 3.8L engines

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 ambient conditions.

The throttle body has an air bypass 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. The inputs are from the throttle position sensor, crankshaft position sensor, coolant temperature sensor, as well as various switch operations (brake, park/neutral, air conditioning). Deceleration die out is also prevented by increasing airflow when the throttle is closed quickly after a driving condition.

TESTING



See Figures 4 and 5

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:



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Fig. Fig. 4: Connect a tachometer to the engine, then start the engine. Observe the idle speed ...



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Fig. Fig. 5: ... then, while observing the idle speed, disconnect a vacuum hose (such as brake booster-to-intake manifold). The IAC motor should compensate for the leak

  1. First attach a tachometer to the engine, then start the engine.
  2.  
  3. 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.
  4.  
  5. Reattach the vacuum hose. The idle should drop, then stabilize.
  6.  
  7. If the engine reacted as indicated, the circuit is probably OK.
  8.  

REMOVAL & INSTALLATION



See Figures 1, 2, 3 and 6



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Fig. Fig. 6: Removing the IAC motor from the throttle body assembly

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the electrical connector from the IAC motor.
  4.  
  5. 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.
  6.  

To install:
  1. 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. (25mm), 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.
  2.  
  3. If the old IAC motor is being installed, place a new O-ring on the motor.
  4.  
  5. Carefully plate the IAC motor into the throttle body and install the retaining screws. Tighten the screws to 17 inch lbs. (2 Nm).
  6.  
  7. Attach the electrical connector to the IAC motor.
  8.  
  9. Connect the negative battery cable.
  10.  

 
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