Electric window motor

Forum: 

Hello i have a Sportrak can any one tell me if the window motor needs an earth going to it? Mine has just gone, so i bought another one from a breakers and thats not working either,i never bolted that one up to the door to test it. Does it need to be bolted to recive an earth? If not could it be elsewhere that it could be? I tested the live going to the motor and thats ok.