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Home >> Scion >> 2005 >> xB Automatic >> Repair and Diagnosis >> Engine Performance >> SFI System >> ECM Power Source Circuit >> Circuit Description
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Circuit Description

When the ignition switch is turned to ON, the positive battery voltage is applied to the coil, which closes the contacts of the EFI main relay (Marked: EFI) and supplies power to terminal +B of the ECM.

If the ignition switch is turned off, the ECM continues to switch on the EFI relay for a maximum of 2 seconds for the initial setting of the throttle valve.