EFI Main Relay (SC300 & SC400)

EFI main relay may also be referred to as EFI relay. EFI fuse supplies constant battery voltage to one side of EFI main relay. When EFI main relay is energized by MREL terminal of Engine Control Module (ECM), EFI main relay provides battery voltage to +B terminal of fuel pump Electronic Control Unit (ECU) and various other electrical components. EFI main relay also provides battery voltage to B and B2 terminals of ECM on SC300 or +B and +B1 terminals of ECM on SC400 of ECM. On all models, for operation of fuel pump ECU, see FUEL PUMP ELECTRONIC CONTROL UNIT (ECU) - (SC300 & SC400) . EFI main relay is located in fuse/relay box at driver's side front corner of engine compartment, near battery.