What was found
DURING TAXI IN, ATTEMPTED APU START. RECEIVED AN AUTO SHUT DOWN AND A FAULT LIGHT. TURNED APU SWITCH TO OFF. AFTER ABOUT 5 MINUTES. FAULT LIGHT EXTINGUISHED. ACFT GROUNDED. ACCOMPLISHED FIM 49-40, TASK 803. APU HAS FAULT MESSAGE 49-41254. STARTER CONVERTER UNIT SHOWS START SYSTEM INOPERATIVE. PERFORMED FIM 49-40, TASK 821. CHECKED CONTINUITY & CLEANED CONNECTORS D1118/P4 TO P6 ON APU STARTER GENERATOR AND START CONVERTER UNIT D1114 TO P6 AT APU STARTER GENERATOR CONNECTOR P6 HAD MOISTURE IN IT. CONTINUITY CHECKS WERE GOOD. STARTED APU FIVE TIMES, FAULT 49-41254 DID NOT STAY ACTIVE ON ANY OF THE STARTS.