After work I headed into the garage to sort out the electric window switches in the van. The switch wiring has 2 purple and black wires, and 2 brown wires, and doesn't make any sign of them being a problem. I swapped the purple and black ones, and it didn't make a difference, but swapping the brown ones reversed the switch, so that now the passenger and driver's side switches were both reversed. I swapped the motor wiring, and everything works fine. I put it all back together and called it done.