Air carrier pilot reported during pre-flight they noticed the green hydraulic pump displayed on and hydraulic pressure was normal with engines not running. Pilot refused to take aircraft in its current condition.

Narrative

During preflight green HYD pump on SD showed pump to be on and HYD pressure normal; though the engine was not running. Maintenance attempted many resets but could not identify the source. Their best suggestion was a bad transmitter because a motoring of the engine by Maintenance showed the pump to operate within parameters. Wanting to apply an MEL to the pump; the Captain wanted clarification on what alerts/ECAMs they would get to indicate a problem with the green system. Unsure; Maintenance offered an engine run to simulate loss of green pump. Maintenance coordinated and performed a dual engine run. During the run the green HYD pump was de-selected to check alerts and verify the PTU would operate as expected. While the PTU appeared to be operating; the symbols on the SD were green; hollow triangles (armed and not operating) and not the solid; green triangles (selected on and operating) we expected to see displayed. Crew verified the system display with the FM and Pelesys modules and found the aircraft SD did not match the reference materials. Maintenance was unable to give any insight why the aircraft images were not as we had been trained to expect. No one was certain if the other anomalies on the HYD SD were related to this. Combined with other operational elements (destination; time of day; time on duty; swapped aircraft; and un-consolidated FO who had never been to ZZZ) Captain elected to code the aircraft. Flight was long delayed"; until the morning and continued without incident with a new air frame."