I dont know why Airbus removed the PTU diagram you mentioned however the information can be found in the Landing Gear chapter in the tables that show interaction between landing gear and other systems.
i.e PTU will run ( if more the 500 PSI pressure diff)
1. Both engine masters off, or
2. Both engine masters on, or
3. Nose wheel not in the towing position and park brake off.
The above applies to “on ground”.