What was found
DURING PUSH BACK ,L ENG HPSOV EICAS STATUS MESSAGE L ENG BLEED LIGHT, L+R DUCT LEAK LIGHTS ALL ILLUMINATED AFTER ENGINE WERE STARTED PACKS + BLEEDS TURNED OFF PER QRH + LIGHTS STAYED ILLUMINATED ENGINES SHUT.AC RETURNED TO GATE AND MAINTENANCE GROUNDED AC , T/S AND FOUND HPC SHORTING PLUG INSTALLED ON HPC CONNECTOR. REMOVED AND STOWED SAME PER MEL MPM 36-11-2. CONDUCTED ENGINE RUNS PER AMM 71-00-00. PNEUMATICS SYSTEM OK. CONDUCTED WING/BODY DUCT LEAK OPERATIONAL TEST PER AMM 26-18-00. TEST OK A/C VERIFIED ETOPS 180. RETURENED AC TO SERVICE . AND DEPARTED