Engine Control Module: Notes

The ECM, through various input sensors, monitors cranking signal, intake air amount, intake air temperature, air/fuel ratio, throttle valve opening angle, No. 1 piston compression stroke TDC, engine coolant temperature, engine RPM, A/C operation, detonation, gear status (if automatic transmission/transaxle) and fuel tank pressure. ECM uses this information to control fuel injection timing and duration, ignition timing, idle speed, A/C cutout, fuel pump, purge control system and performs self-diagnostic functions.

ECM includes On Board Diagnostics-II (OBD-II) to monitor efficiency of emissions-related components and systems. If an emissions-related system malfunctions or deteriorates below preprogrammed performance criteria, OBD-II will illuminate the Malfunction Indicator Light (MIL) and store a Diagnostic Trouble Code (DTC). If a condition exists that may cause catalytic converter damage, MIL will flash continuously.