Lumina V6-3.1L VIN J (2000)
Diagnostic Chart (Part 2 Of 2)
CIRCUIT DESCRIPTION
The PCM controls engine idle speed by adjusting the position of the Idle Air Control (IAC) motor pintle. The IAC is a bi-directional motor driven by
two coils. The PCM pulses current to the IAC coils in steps (counts) to extend the IAC pintle into a passage in the throttle body to decrease air flow.
The PCM reverses the current pulses to retract the pintle, increasing air flow. This method allows highly accurate control of idle speed and quick
response to changes in engine load.
DIAGNOSTIC AIDS
Inspect for the following conditions:
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Restricted air intake system-Inspect for a possible collapsed air intake duct, restricted air filter element, or foreign objects blocking the air intake
system.
