Tundra 2WD V6-4.0L (1GR-FE) (2005)
Engine Control Module: Component Tests and General Diagnostics
ECM POWER SOURCE CIRCUIT
CIRCUIT DESCRIPTION
When the ignition switch is turned ON, battery positive voltage is applied to terminal IGSW of the ECM and the EFI relay control circuit in the ECM
sends a signal to terminal MREL of the ECM switching on the EFI relay.
This signal causes current to flow to the coil, closing the contacts of the EFI relay and supplying power to terminal +B of the ECM.
Wiring Diagram