What was found
AFTER LANDING, APU WOULD NOT START AFTER 2 ATTEMPTS. GROUNDED - YES. DURING INITIAL EVALUATION FOUND ACTIVE FAULT 49-41254, REF B737-9 IFIM TASK 49-40-00-810-818. INSPECTED APU STARTER GENERATOR ELECTRICAL CONNECTOR AND THE HARNESS, NO DEFECT FOUND, REF B737-9 AMM TASK 49-11-01-200-801. CHECKED THE HARNESS BETWEEN APU START CONVERTOR CONNECTOR , D11114B AND THE APU STARTER/ GENERATOR CONNECTOR, P6, RESULT NO DEFECT FOUND REF B737-9 WDM 49-41-11 AND AMM 49-41-61-000-801. REMOVED AND REPLACED APU START CONVERTOR UNIT IAW AMM 49-41-61/401 RESULTS THE FAULT 49-41254 CHANGED TO NOT ACTIVE. THERE IS NO ACTIVE FAULT INDICATED NOW.