What was found
FLIGHT 3391, LT INTAKE LIGHT CYCLING. LIGHT ON FOR 6 SECONDS, OUT OF 1:30 THEN REPEATS CYCLE. AIR RETURN TO DTW. MAINTENANCE REPLACED LT DE-ICE MODULE IAW SF340, MM CHAP 30 P/N 44730-1, S/N OFF A00022, S/N ON A00461. RAN A/C FOR 30 MINUTES. NO FAULTS NOTED. SYSTEM OPERATES NORMAL.