Circuit Description

When the ignition switch is turned on, battery positive voltage is applied to terminal IGSW of the ECM and the EFI relay (Marking: EFI) control circuit in the ECM sends a signal to terminal MREL of the ECM switching on the EFI relay.

This signal causes current to flow to the coil, closing the contacts of the EFI, relay and supplying power to terminals +B of the ECM.