Citroen C5 2007 estate rear wiper not working

[simmsimmtwo]

Hi there can anyone help. I just bought a 57 plate C5 estate the rear window wouldn't open or wiper work. I have fixed the rear window problem but still stuck on the wiper. Blade is stuck at 11oclock position.
How do I check if wiper motor is working as 3 wires to it blue white and black ? Which is which ? And what should be output ? Or resistance across motor
Thank you