Engine Control Module: Description and Operation

PURPOSE
Preprogrammed performance data and information from vehicle sensors, the Powertrain Control Module (PCM) develops an adaptive strategy for operating the ignition, fuel, and EGR systems. The powertrain control module will also adjust the electronically controlled automatic transmission.

OPERATION
The PCM receives data from various inputs (sensors):

- Throttle Position (TP) sensor

- Mass Air Flow (MAF) sensor

- Intake Air Temperature (IAT) sensor

- Engine Coolant Temperature (ECT) sensor

- Heated Oxygen Sensor (HO2S) (one set for engine control and one set for catalyst monitoring)

- Camshaft Position (CMP) sensor

- Crankshaft Position (CKP) sensor

- Power Steering Pressure (PSP) switch

The PCM contains specific calibrations for optimizing emissions controls, fuel economy, and driveability. Based on information received and programmed into its memory, the processor sends signals to control various outputs (actuators):

- Fuel injector

- Ignition coil(s)

- Idle Air Control (IAC) valve

- EGR vacuum regulator control

NOTE: If the vehicle's battery is disconnected, there may be some abnormal driving symptoms until the powertrain control module relearns its adaptive strategy. The vehicle may need to be driven 10 miles or more to relearn the strategy.