ECM Power Source Circuit: Description

When the ignition switch is turned ON, the positive battery voltage is applied to terminal IGSW of the ECM. The ECM MREL output signal causes a current to flow to the coil, closing the contacts of the EFI relay (Marking: EFI) and supplies power to terminal +B of the ECM.

If the ignition switch is turned OFF, the ECM continues to switch on the EFI relay for a maximum of 2 seconds for the initial setting of the throttle valve.