What was found
DURING TAKEOFF FROM DLG LT HYDRAULIC PRESSURE WARNING LIGHT ILLUMINATED WHEN TAKEOFF POWER WAS APPLIED AND WENT OUT WITH POWER REDUCTION. TAKEOFF WAS ABORTED AND CREW PERFORMED RUNUP. PRESSURE GAUGE WAS READING NORMAL WITH LIGHT ILLUMINATED. ANC MX DEFERRED PRESSURE WARNING SYSTEM BY PHONE AND FLIGHT CONTINUED NORMALLY. AFTER AIRCRAFT RETURNED TO ANC, MX CLEARED DEFERRAL BY REPLACING WARNING LIGHT PRESSURE SWITCH.