What was found
EICAS MESSAGE L GEN OFF DISPLAYED. L GEN OFF LIGHT ILLUMINATED GENERATOR RESET DID NOT CORRECT, CONDITION, EICAS MESSAGE L AC BUS DISPLAYED. L BUS OFF LIGHT REMAIN ILLUMINATED WITH APU GEN LIGHT EXTINGUISHED BUS TIE RESET NORMAL. BITE THE BPCU IAW FIM 24-20-00 FAULTED. OVER VOLTAGE TRI GEN/WIRING/GCU. CHECK WIRING FROM GCU TO IDG WIRING CHECKED OUT GOOD CLEANED CONNECTOR PLUG D10966 RAN ENGINE IDG OPS NORMAL. CHANGE LT GCU AS PRECAUTIONARY IAW AMM 24-22-02. OPS CHECK NORMAL, OK FOR SERVICE.