What was found
DURING NR 2 ENGINE START, LOST COCKPIT ELEC POWER. T-R MSG DISPLAYED ON LOWER EICAS. REPLACED LEFT TRU, NO HELP. LEFT ENG DID NOT TRANSFER PWR. SWAPPED LEFT AND RIGHT GCU, NO HELP. SWAPPED BACK. REPLACED LEFT GEN CNTL BREAKER C901 AND LEFT BUS TIE CNTL BREAKER C902, NO HELP. FOUND WIRE BROKEN AT LEFT GEN CONTROL SWITCH OVERHEAD PANEL. REPAIRED PER GNMM. CHECK OK, ENGINES RUN AND CHECKS OKAY.