Passenger window don't work

[Halon]

OK well the other day my passenger window just decided it wouldn't go down. I thought maybe the motor was dead. Today we popped off the door panel. We seen the plug that goes directly to the motor with either 12 or -12V. We unplugged it, hooked up a 12V battery. The motor works. So we connected a multimeter to the other end of the plug to see what Voltages we were getting when we hit the UP/DOWN window switch. We are getting 13.1V when we hit up, which sounds good to me. But when I switch it to DOWN we get like -1V. I'm guessing this is a problem where I'd have to chase wires all the way through the car to fix this. I'm just checking to see if anyone had this happen before or has any good quick checks I can make. Thanks!

Also it does not go down no matter if I use the passenger or driver side switch in case you are wondering.