The internal fuse box is behind the cover down and to the right of the steering wheel. There is a diagram of the fuse box in the handbook and there should be symbols on the back of the cover you had to remove to find which fuse it is.
I would check the connector plates on the tailgate as they can get damaged and cause this sort of problem.
Alternatively the motors are prone for seizing up and would need replacing.
a girl, September 2008
