Power window won't go down...

[HyperactiveSloth]

OK, here's the breakdown. The passenger side window on an '01 Sport Trac appears to work fine (can hear the slight sound and slight dim of interior lights) when the Up button on either switch is pressed, but does not roll down if the Down button is pressed on either switch. The passenger side switch itself is lighted and when either Down button is pressed the light inside the switch goes out. The switch has just been replaced and behaves exactly as the old one did. I tested the voltage at the motor connector and had 12v to the yellow/red wire, but when testing the red/yellow wire I realized that it always has continuity to ground no matter which way the switch is pressed. I figured that wire itself may have grounded out so I bypassed it with a new wire. Unfortunately, it was not that simple. I still have continuity to ground on that wire all the time (which explains why the Down won't work, because it needs to reverse polarity and make that wire hot). I was in the process of doing some more tests on each of the 5 wires but only managed to confuse myself. When I tried again so I could right down each wires voltage/continuity readings in each state (static/Down/Up) I accidentally broke my voltmeter and can't remember for sure what any of the readings I'd already took were.

I'm hoping someone here might know enough about how the window circuitry works that the few clues I have are enough to narrow down which wire is being the culprit. Any ideas? (Much thanks in advance for any help you can give.)