Highlander 4WD V6-3.3L (3MZ-FE) (2004)
Engine Control Module: Component Tests and General Diagnostics
ECM POWER SOURCE CIRCUIT
CIRCUIT DESCRIPTION
When the ignition switch is turned ON, battery voltage is applied to terminal IGSW of the ECM. The ECM "MREL" output signal causes current to flow
to the coil, closing the contacts of the EFI main relay (Marking: EFI) 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 allow for the initial setting of the throttle valve.
Wiring Diagram