Main Relay Control: Notes

When the ignition switch is turned ON, battery voltage is applied from the ignition switch to the ECU, turning ON the ignition power transistor and energizing the MFI control relay coil. This turns the MFI control relay switch ON, and supplies power from the battery to the ECU through the MFI control relay switch.

After the ignition switch is turned OFF, battery voltage is supplied to Main relay for 8 seconds. ECU remembers and calculates the data.