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Home >> Lexus >> 1998 >> ES 300 >> Repair and Diagnosis (Single Page) >> Engine Performance >> Theory and Operation >> Engine Controls - Theory & Operation >> Computerized Engine Controls >> ECM Power Source >> Ignition Keyed Power
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Ignition Keyed Power

When the ignition switch is turned on, the ECM grounds the control circuit (coils) of the EFI main relay. This supplies battery power to the ECM. This circuit is also protected by the EFI fuse.