ECU Power Supply
POWER SUPPLYOPERATION
^ While the ignition switch is on, battery power is supplied to the engine control unit, the injector, the air flow sensor, etc.
^ When the ignition switch is turned on, current flows from the ignition switch through the control relay coil to ground. This turns on the control relay switch and power is supplied from the battery through the control relay switch to the engine control unit.
Inspection Using Multi-use Tester
Harness Inspection