EFI Main Relay (Non-Turbo)

The EFI No. 1 fuse (30-amp) supplies constant battery voltage to EFI main relay. EFI No. 1 fuse and EFI main relay are located in fuse/relay box at driver's side front corner of engine compartment, near the battery. The EFI main relay is turned on by M-REL terminal of Engine Control Module (ECM). When EFI main relay is turned on, voltage is supplied to +B and +B2 terminals of ECM, data link connector No. 1, +B terminal of fuel pump Electronic Control Unit (ECU) and various other electrical components. Fuel pump ECU is located in driver's side rear corner of trunk. See Figure. Fuel pump operating speed is controlled by the operating condition of the engine such as: starting, light load or heavy load. The ECM delivers an input signal voltage signal from FPC terminal on ECM to FPC terminal on fuel pump ECU in accordance with the engine operating condition. The fuel pump ECU uses this input signal to determine how much voltage should be delivered to the fuel pump for varying fuel pump operating speed.