[Mysterytrain]

You can rule out a power issue because the passenger door switch works. That indicates that there is 12 volts on the driver's door Passenger switch.
I think you have a bad ground connection on the switch that is not working. Attach a wire to terminal 4 and clip it to the metal door frame and see if it works. The next guess is the switch is bad. If the internal sliding contacts aren't moving then the switch never provides a ground. If you want to experiment swap switches. It might just make more sense to install a new one.