Engine Warm-Up

THIS IS AN OPEN LOOP MODE.
During engine warm-up, the Powertrain Control Module (PCM) receives input from:
^ Battery voltage

^ Crankshaft position (CKP) sensor

^ Engine coolant temperature (ECT) sensor

^ Intake air temperature (IAT) sensor

^ Manifold absolute pressure (MAP) sensor

^ Throttle position sensor (TPS)

^ Camshaft position (CMP) sensor

^ A/C select switch (if equipped)

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.

^ Adjust engine idle speed through the IAC motor.

^ Adjust ignition timing.

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

^ Operate the Up-Shift indicator light.

^ Begin to monitor oxygen sensor. When engine is at operating temperature, the system will leave warm up mode and go into closed loop operation.