What was found
FLIGHT 3188 - LGA-PWM - AT APPROXIMATELY 1500 FEET ON FINAL APPROACH WHEN THE GEAR WAS SELECTED DOWN, RECEIVED EICAS MESSAGES "E2 HYD PUMP FAIL" AND "RUDD SYS 2 INOP". IMMEDIATELY CHECKED HYDRAULICS PAGE AND THE ELECTRIC PUMP WAS ON AND THE FLUID LEVEL WAS NORMAL. BEGAN CHECKLISTS AND DECLARED AN EMERGENCY. AT THIS POINT "RUDD SYS 2 INOP" MESSAGE DISAPPEARED AND ALL SYSTEMS WERE OPERATING. LANDED IMMEDIATELY AND TAXIED TO GATE WITHOUT FURTHER INCIDENT. MAINTENANCE REMOVED AND REPLACED THE NR 2 HYDRAULIC PUMP.