RAM 1500 Truck 2WD V6-3.9L VIN X (1999)
Idle Speed/Throttle Actuator - Electronic: Description and Operation
IDLE AIR CONTROL (IAC) MOTOR-PCM OUTPUT
MAP And Throttle Position Sensor Location - Typical
The IAC motor is mounted to the back of the throttle body and is controlled by the powertrain control module (PCM).
Throttle Body Air Control Passage
The throttle body has an air control passage that provides air for the engine at idle (the throttle plate is closed). The IAC motor pintle protrudes
into the air control passage and regulates air flow through it. Based on various sensor inputs, the powertrain control module (PCM) adjusts engine
idle speed by moving the IAC motor pintle in and out of the air control passage. The IAC motor is positioned when the ignition key is turned to the
On position.
A (factory adjusted) set screw is used to mechanically limit the position of the throttle body throttle plate. Never attempt to adjust the engine idle
speed using this screw. All idle speed functions are controlled by the PCM.
