Component Tests: Ecu
First check the ECU ground circuit. If it is faulty, repair it. If it is normal, the ECU could be faulty, so replace the ECU and check if the symptoms appear. Measure the resistance between the ECU ground terminal and the body ground. Resistance: 1Ω or less. Disconnect the ECU connector, check the ground terminals on the ECU side and the wire harness side for bend and check the contact pressure. See Fig 1.