Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

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Idle

THIS IS A CLOSED LOOP MODE.
With engine idling at operating temperature, the Powertrain Control Module (PCM) receives inputs from:

^ Air Conditioning Control Position (if equipped)

^ Battery voltage

^ Camshaft position (CMP) sensor

^ Engine coolant temperature (ECT) sensor

^ Manifold absolute pressure (MAP) sensor

^ Intake air temperature (IAT) sensor

^ Crankshaft position (CMP) sensor

^ Throttle Position Sensor (TPS)

^ Heated oxygen sensor (HO2S)

Based on these inputs the PCM will:
^ Apply voltage to the injectors. The PCM then controls injection sequence and pulse width by switching individual injector ground paths on and off.

^ Monitor oxygen sensor and fine tune air/fuel ratio by varying injector pulse width.

^ Adjust engine idle speed through the IAC motor.

^ Adjust ignition timing.

^ Operate A/C Compressor Clutch relay (if equipped and selected).