ECM Power Source Circuit [10/2014 - ]: Description

When the power switch is turned on (IG), auxiliary battery voltage is applied to the IGSW terminal of the ECM. The output signal from the MREL terminal of the ECM causes current to flow to the coil of the EFI-MAIN relay, closing the contacts of the EFI-MAIN relay and supplying power to terminals +B and +B2 of the ECM.