What was found
APU WILL NOT MAINTAIN ELECTRICAL LOAD AT GATE. THREE LIGHTS OUT, APU GENERATOR OFF, BUSS OFF, LIGHT OFF, DIM-FULL BRIGHT, PUT APU BUSS ON, FAILED AGAIN. HAD TO TURN ELECTRICAL HYD PUMPS & WINDOW HEAT OFF FOR APU GENERATOR TO STAY ON LINE. ACFT GROUNDED. ACCOMPLISHED FIM 24-21 TSK 820, FOUND CONNECTOR D11118 LOOSE. INSPECTED, RESEATED CONNECTOR PERFORMED REPAIR CONFIRMATION IAW 49-11-00. LOADED GENERATOR FOR APPROX 10 MINUTES WITH ELECTRICAL HYD PUMPS, WINDOW HEAT, EXTERIOR LIGHTS, AND GALLEY POWER, ALL OPS NORMAL.