The alternator wiring won't straight go to the ECU, but instead on the fuse box where by it powers every little thing else in the vehicle including the ECU. The alternator will use 12V on E2 so there isn't any much more ground for your battery mild, only 12V. Hence https://toyota-4a-ge49258.full-design.com/how-much-you-need-to-expect-you-ll-pay-for-a-good-blacktop-4age-for-sale-75048633