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Home >> Lexus >> 2003 >> GX 470 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Computerized Engine Controls >> Engine Control Module (ECM) Power Source Circuit (Ignition On) >> Circuit Description

Circuit Description

When ignition switch is turned on, 9-14 volts is applied to terminal IGSW at ECM. EFI relay control circuit in ECM then sends a signal to terminal MREL at ECM to switch EFI relay on. This signal causes current to flow to coil, closing contacts of EFI relay and supplying power to terminal +B of ECM. If ignition switch is turned off, ECM continues to switch on EFI relay for a maximum of 2 seconds for initial setting of throttle valve.