Idle Speed/Throttle Actuator - Electronic: Description and Operation

Fig. 31 Idle Air Control Motor:

PURPOSE
The Idle Air Control (IAC) motor is mounted on the throttle body. The PCM operates the idle air control motor Fig. 31. The PCM adjusts engine idle speed through the idle air control motor to compensate for engine load, coolant temperature or barometric pressure changes.

OPERATION
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 air flow through it.

The PCM adjusts engine idle speed by moving the IAC motor pintle in and out of the bypass passage. The adjustments are based on inputs the PCM receives. The inputs are from the throttle position sensor, crankshaft position sensor, coolant temperature sensor, MAP sensor, vehicle speed sensor and various switch operations (brake, park/neutral, air conditioning and power steering).

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 57 of the PCM connector
- Circuit K40 connects to cavity 48 of the PCM connector
- Circuit K59 connects to cavity 58 of the PCM connector
- Circuit K60 connects to cavity 49 of the PCM connector