Grand Cherokee 2WD L6-242 4.0L VIN S MFI (1993)
Idle Speed/Throttle Actuator - Electronic: Description and Operation
IAT And TPS Sensors
LOCATION
Idle Air Control (IAC) motor is mounted on throttle body.
PURPOSE
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 maintains 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.
Deceleration stall is also prevented by increasing the airflow when the throttle is closed suddenly
The PCM calculates proper idle speed using information from throttle position, vehicle speed, and coolant temperature sensors and brake, and
neutral/safety switches.
