What was found
AIRCRAFT HAD AN APU FIRE INDICATION DURING INITIAL CLIMBOUT, FOLLOWED PROCEDURES, AND RETURNED TO THE FIELD. MAINTENANCE INSPECTED THE APU AREA, CHECKED ALL PNEUMATIC DUCTS AND SEALS FOR LEAKS AND NO DEFECTS (LEAKS) WERE FOUND. INSPECTED APU OVERHEAT DETECTION SYSTEM, AND FOUND INTERMITTENT SHORT TO GROUND AT CONNECTOR D4934P, PINS A & C. REPLACED APU TAILPIPE OVERHEAT DETECTOR LOOP M717 AND HARNESS M9324. APU FIRE DETECTION SYSTEM CHECKED GOOD AND AIRCRAFT WAS RETURNED TO SERVICE.