The same as the other posts. The Window Motors are not grounded through the Chassis as your Starter Motor is; so testing them that way is not going to work.

The most common reason a window does not work is the Switch (find the DIY on taking the Switch apart and cleaning the contacts; I scraped mine with a small pocket knife), 2 windows diagonal to each other on opposite sides the a Fuse, followed by broken Wires and lastly an issue with the Motor; Brushes or gummed up bushings.

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84 300D, 82 Volvo 244Gl Diesel