Electronic Control Module: Notes

The ECM analyzes information from engine sensors and uses that information to control output devices. On feedback carburetor system, ECM sends a signal to mixture control (duty) solenoid, which controls air-fuel mixture ratio through main metering circuit.

Once vehicle reaches operating temperature, ECM controlling signal cycles mixture control solenoid between on-and-off time (duty cycle), according to sensor input. Control signal generated by ECM is selected from 4 operational modes: Inhibit, Open Loop, Wide Open Throttle (WOT) and Closed Loop.