Electronic Control Module (ECM): Notes

The ECM gathers information from various input devices and uses this 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 according to sensor input, ECM sends control signals to cycle mixture control (duty) solenoid between on-and-off time (duty cycle). Control signal generated by ECM is selected from 4 operational modes: inhibit, open loop, Wide Open Throttle (WOT) and closed loop. Inhibit Mode A fixed control signal is sent to mixture control solenoid in this mode.