What was found
SEA FLIGHT NR 2321: DEICE PRESSURE CAUTION LIGHT ILLUMINATED. RAN CHECKLIST. LIGHT EXTINGUISHED THEN CAME ON AGAIN. NOTED THAT THE SECOND INDICATOR LIGHT ON THE RIGHT WING WAS SLOW TO ILLUMINATE AND WOULD FLICKER WHEN ILLUMINATED. ALL OTHER INDICATIONS WERE NORMAL. MAINTENANCE PERFORMED FUNCTIONAL TEST OF THE AIRFRAME PNEUMATIC DEICING SYSTEM IAW Q400 AMM 30-11-00-720-801. RAN ALL CYCLES IN MANUAL, ISO, NORM WITH BOTH ENGINES AND NR 1 AND NR 2 INDEPENDENTLY. DEICE PRESS CAUTION DID NOT RETURN. ALL BOOT INDICATIONS AND INFLATION CYCLES CHECK NORMAL. ALL OPS CHECK GOOD AT THIS TIME. NO FURTHER DEFECTS NOTED. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.