I know I have a different model car (85 wagon) but it I had the same problem.
As it turned out I had broken wires. Two of the wires that led from the center console to the motor/switch in the door were cracked/broken in half from years of opening and closing the door. They were broken right at the hing where they enter the door. I ended up cutting out about a foot of old wire and reconnecting it with in-line splices and new wire.
If you have a wiring diagram and a continuity tester check the continuity of the wires between the switch in the door and the console. Your problem sounds exaclty like mine.
85 300TD Turbodiesel 299,376 miles