The drivers side window switch will not work. drivers side passenger window switch will not work. passenger side window works. drivers switch in up position only 1.5 volts to motor. drivers side passenger window switch in up position 1.6 volts. changed switch no change. ?
Can’t say that I have ever heard of a Plymouth Montana. A Pontiac Montana I have though.
Anyway, the issue would be in the wiring. You have one pinched or shorted. Most likely in the door jam area of the drivers side. This is the most common area as the drivers side door usually gets operated the most. As vehicles get older the wiring begins to get brittle and break. This would be the first place I would look since you already tried the switch.
Window Switch Wiring Diagram
