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Home >> Lexus >> 2003 >> ES 300 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Computerized Engine Controls >> ECM Power Source Circuit (Ignition On) >> Circuit Description
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Circuit Description

When ignition switch is turned on, 9-14 volts is applied to the terminal IGSW at ECM main relay control circuit, sending a signal to terminal MREL at ECM, which then switches EFI main relay on. When ignition is turned off, ECM will keep EFI main relay on for 2 seconds or less in order to reset Idle Air Control (IAC) valve.

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