Code 20A503?

Car was leaking coolant from the oil filter housing. Had that changed and since then the drivetrain message keeps appearing. Drives fine with no issues or check engine light. Removed the harness from the turbo coolant auxiliary pump and it shows open circuit. Checked and found 1 ground then with ignition on another ground, bt not sure if I can get a 5v from the 3rd wire while the car is running and cold or I have to wait till after the car is warm and then shut it off and see if I get a signal, because all this pump does is cool turbo after shut off.
Code 20a503