What was found
YELLOW HYD PUMP LOW PRESS. WHEN ACFT RETURNED TO GATE ALL HYD INDICATIONS WERE NORMAL & THE HYD QUANTITIES WERE AT NORMAL LEVELS. PERFORMED A GND ENG RUN TO SEE IF THE FAULT WOULD RETURN. AFTER ENG START & OPERATION OF THE FLIGHT CONTROLS, THE FAULT RETURNED. THEY GOT A YELLOW PUMP LOW PRESS & YELLOW SYS LOW PRESS ECAM MSG ALONG WITH AN OVERHEAD ENG YELLOW PUMP, LO PR LIGHT, A YELLOW SYS SERVO CTL, LO PR, LIGHT AS WELL AS A SPOILER FAULTS FOR THE YELLOW SYS. AFTER ENG SHUTDOWN WE FOUND THE OVERHEAD YELLOW ENG PUMP, LO PR, LIGHT WAS NOT ILLUMINATED WITH NO PRESS ON SYS. R & R NR 2 ENG DRIVEN YELLOW SYS HYD PUMP IAW MM 29-11-32-04-02. OK FOR SERVICE IAW MM 29-11-32-04-02.