Grand Cherokee 2WD V8-5.2L VIN Y (1998)
Idle Speed/Throttle Actuator - Electronic: Description and Operation
IDLE AIR CONTROL (IAC) MOTOR-PCM OUTPUT
Fig 10 MAP & TPS Location
The IAC motor is mounted to the back of the throttle body (Fig. 10) and is controlled by the Powertrain Control Module (PCM).
Fig. 17 Throttle Body Air Control Passage - Typical V8
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 (Fig. 17) 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.
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.
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Circuit K39 connects to cavity A20 of the PCM
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Circuit K40 connects to cavity A11 of the PCM
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Circuit K59 connects to cavity A10 of the PCM
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Circuit K60 connects to cavity A19 of the PCM