What was found
PIT - FLT 2004 - ON CLIMB-OUT FROM PIT, EN ROUTE TO LGA, THE CREW NOTED AN ENGINE OVERHEAT WARNING ON THE NR 2 ENGINE. THE A LOOP FOR THE NR 2 ENGINE WAS ON MEL AT THE TIME. THE WARNING WAS AT FIRST INTERMITTENT THEN BECAME STADY AS THE AIRCRAFT CROSSED THROUGH 10,000 FEET. CREW ACCOMPLISHED PROCEDURES AND SHUTDOWN THE NR 2 ENGINE. AN EMERGENCY WAS DECLARED AND THE FLIGHT RETURNED TO FIELD AT PIT. FLIGHT LANDED WITHOUT FURTHER INCIDENT. TOTAL SINGLE ENGINE TIME WAS 13 MINUTES. MAINTENANCE REMOVED AND REPLACED THE NR 2 ENGINE FIRE WARNING SOFT CORE HARNESS. ALSO, REMOVED AND REPLACED THE NR 2 ENGINE FAN LOWER FIRE LOOP (P/N 6676) AND FIREWALL LOOP (P/N 6672-01). OPERATIONAL CHECK GOOD. RAN ENGINE TO