Idle Speed/Throttle Actuator - Electronic: Description and Operation

IAC Motor 3.3L:

FUNCTION
Motor maintains optimum idle speed under varying engine loads, and prevents deceleration die out.

OPERATION
The Idle Air Control (IAC) motor controls air flow through a passage connected to both intake manifold plenums. The PCM controls engine idle speed, by adjusting the IAC motor to compensate for engine load or ambient conditions.

The IAC varies the amount of air that is allowed to bypass the throttle blades. It does this by extending or retracting the IAC pintle into the idle air passage. The further the IAC pintle protrudes into this passage the slower the idle speed, and the less the IAC pintle protrudes the greater the idle speed.

The PCM calculates proper idle speed using information from throttle position, vehicle speed, and coolant temperature sensors and brake, and neutral/safety switches.

CIRCUIT OPERATION
The Powertrain Control Module (PCM) operates the idle air control motor through 4 circuits - K39, K40, K59, and K60. Each circuit connects to separate cavities in the PCM connector.
- Circuit K39 connects to cavity 39 of the PCM connector.
- Circuit K40 connects to cavity 40 of the PCM connector.
- Circuit K59 connects to cavity 59 of the PCM connector.
- Circuit K60 connects to cavity 60 of the PCM connector.