As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH GEAR SELECTED DOWN AND LOCKED (3 GREEN, NO RED) SELECTED FLAP SWITCH TO 15 AND 'HYD' PRESSURE LIGHT CAME ON FLASING WITH MASTER CAUTION FLASHING INSTANTLY WITH NO DELAY.TROUBLESHOT TO FAULTY ANNUNCIATOR PANEL. REPLACED WITH SERVICEABLE UNIT. OPERATIONAL CHECK NORMAL IAW CESSNA 560XL MM 31-50-01.