LS 460 V8-4.6L (1UR-FSE) (2007)
Engine Control Module: Component Tests and General Diagnostics
ECM Power Source Circuit
DESCRIPTION
When the engine 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 MAIN2 relay and supplying power to terminal +B and +B2 of the ECM.
If the engine switch is turned off, the ECM holds the EFI MAIN2 relay ON for a maximum of 2 seconds to allow for the initial setting of the throttle
valve.
When the engine switch is turned on (IG), voltage from the ECM's MREL terminal is applied to the EFI MAIN2 relay. This causes the contacts of the
EFI MAIN2 relay to close, which supplies power to terminal +B and +B2 of the ECM.
Wiring Diagram