Toyota 2GR-FE Manual page 596

ES–440
2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ECM Power Source Circuit
DESCRIPTION
When the ignition switch is turned on (IG), the battery voltage is applied to terminal IGSW of the ECM.
The ECM MREL output signal causes a current to flow to the coil, closing the contacts of the EFI MAIN
relay and supplying power to terminal +B of the ECM.
If the ignition switch is turned off, the ECM holds the EFI MAIN relay ON for a maximum of 2 seconds to
allow for the initial setting of the throttle valve.
When the ignition switch is turned on (IG), voltage from the ECM's MREL terminal applies to the engine
room junction block (EFI relay). This causes the contacts of the engine room junction block (EFI relay) to
close, which supplies power to terminal +B or +B1 of the ECM.
ES