What was found
AT ROTATION THE FIRE DETECTION LIGHT ON THE FOREWARD PANEL AND THE FAULT LIGHT ON THE S/O PANEL FLASHED (4 TO 5 TIMES). THE NACELLE TEMP GAUGE NR 4 ENGINE, A LOOP WAS FLUCTUATING BETWEEN 3 AND 8. DUE TO PREVIOUS HISTORY RETURNED TO LAND. RETURNED TO YWG AND LANDING WAS UNEVENTFUL. MAINTENANCE PREPARED AIRCRAFT FOR A 3 ENGINE FERRY FLIGHT TO MSP FOR REPAIRS. MAINTENANCE FOUND NR 4 ENGINE GENERATOR WIRES WERE CHAFED AND SHORTED TO NR 4 ENGINE A LOOP. REMOVED AND REPLACED NR 4 ENGINE. OPERATIONAL CHECKED GOOD, AND AIRCRAFT RETURNED TO SERVICE.