wipers and sunroof aren't working with engine on
 

Ok so this has been going on since i got my 89 GTU a little over a year ago. When the car is on but not running the wipers and sunroof will work fine but when the engine is running they won't do anything. They used to work after it ran for a little bit but now they cease to do anything while the car is running. Does anyone have any idea what it could be? I need this fixed before i take it to be inspected. Please help and thanks in advance.