I would check the contacts on the drivers door plug. When I went through my car, a lot of those contacts were corroded. I scraped them with a mini screwdriver, and smashed them closed (not completely closed) to create a better contact. If you tested the new switches on the other windows and it proved to work, then the switch is the known good. You would start at the contacts for the drivers door, then work your way back. I hope that this helps.