The alternator wiring doesn't instantly go to the ECU, but somewhat to the fuse box exactly where it powers all the things else in the vehicle such as the ECU. The alternator will use 12V on E2 so there's no far more ground for that battery mild, only 12V. So https://toyota-4age73159.answerblogs.com/32742959/rumored-buzz-on-4age-blacktop-engine-for-sale