What was found
AUTO THROTTLE DISCONNECTED ON DESCENT WITH LEFT ENGINE CONTROL ROLL EICAS MSG. RE-ENGAGED AUTO THROTTLE AND DISCONNECTED AGAIN. INTERMITTENT HARNESS PROBLEM BETWEEN THE PERMANENT MAGNET ALTERNATOR (PMA) AND THE ELECTRONIC ENGINE CONTROL (EEC) CAUSED THE EEC A-CHANNEL TO SET THE A-CHANNEL POWER FAIL MESSAGE WITH ENGINE REVERSION TO ALTERNATE MODE OPERATION. AUTO THROTTLE IS NOT OPERABLE IN THE ALTERNATE (N1) MODE. ENGINE WAS REPLACED. ENGINE HARNESS BETWEEN THE PMA AND EEC WAS REPLACED ALONG WITH THE PMA AND EEC. TEST CELL RUN CONFIRMED NORMAL OPERATION. HARNESS IS UNDER INVESTIGATION.