Passenger Side Power Window Circuit

The power window would not roll down on the passenger side of my 2005 Dodge Status SXT. I replaced the window motor, but this did not fix the problem. When not installed, but plugged into the wire harness the motor only runs one direction (up). There are only two wires that run to the motor. When I hook a multi meter up to the two wires and press the switch up I get +12 volts. But when I press the switch down I get -0.00 volts. I tried the same thing on the rear passenger door and when I press the switch up I get +12 volts, and when I press it down I get -12 volts.

The crazy thing is that if I hook the negative lead of the multi meter to a metal ground on the door and use the positive lead on each of the terminals (one at a time) within the harness I can get 12 volts at each one with the switch in the corresponding up or down position.

It is like both wires are providing positive voltage, but one of the two wires is not providing a ground when the switch is in the down position?

Any ideas, please help!

Bad switch. 12 volts on both sides tells us the switch is not grounding. Since the window goes down we know that there is good power and good ground available.