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Home >> Lexus >> 2003 >> IS 300 Base, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 55 (Engine Controls - System & Component Testing) >> Computerized Engine Controls >> Engine Control Module (ECM) Power Source Circuit (Ignition On) >> Circuit Description
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Circuit Description

WARNING: This page is about a different car, the 2003 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.

When ignition switch is turned on, 9-14 volts is applied to terminal IGSW at ECM. EFI or ECD relay control circuit in ECM then sends a signal to terminal MREL at ECM to switch EFI or EDC relay on. This signal causes current to flow to coil, closing contacts of EFI or ECD relay and supplying power to terminal +B of ECM.

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