ECM Power Source Circuit [09/2014 - 10/2015]: 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 No. 1 integration relay (EFI MAIN1 relay) and supplying power to terminal +B and +B2 of the ECM.

If the engine switch is turned off, the ECM holds the No. 1 integration relay (EFI MAIN1 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 No. 1 integration relay (EFI MAIN1 relay). This causes the contacts of the No. 1 integration relay (EFI MAIN1 relay) to close, which supplies power to terminal +B and +B2 of the ECM.