What was found
WING A/I L VALVE REMAINED ON W/ ANTI ICE SWITCH ON QRH FOLLOWED - NO RESOLUTION. GROUNDED - YES. PERFORMED B737-9 IFIM TASK 30-11-00-810-808. VALVE STAYS CLOSED DURING BOTH ON/OFF SELECTION WITH LIGHT STAYING ON. PERFORMED HEALTH CHECK PER FIM STEP C REF B737-9 AMM 30-11-11-200-801. CYCLED WAIV AS NEEDED TO CLEAR MOISTURE BLOCKAGE. VALVE OPERATES NORMALLY. FLIGHT DECK LIGHT EXTINGUISHES NORMALLY BOTH IN ON/OFF POSITION. WAIV OPERATES NORMALLY. AIRCRAFT RELEASED REF FIM 30-11-00-810-808.