ECM Power Source Circuit [11/2023 - ]: Description
WARNING: This page is about a different car, the 2025 Toyota Corolla Cross and 2024 Toyota Corolla Cross. However, it is still accessible from the selected car via links, so may be relevant.
When the ignition switch is turned to ON, the auxiliary battery voltage is applied to the IGP terminal of the ECM. The output signal from the MREL terminal of the ECM causes current to flow to the coil of the EFI-MAIN NO. 1 relay, closing the contacts of the EFI-MAIN NO. 1 relay and supplying power to terminals +B and +B2 of the ECM.