help with power windows

so ive been installing my alarm in my car with a dude i got thats done this for 3 years, doing audio and installs on alarms and such but my passenger window got us. it always rolls down fine, but sometimes it wont go back up. we got it to do this and whats happening is when it goes down one wire to the motor is 12v and the other ground, then when it goes back up you know it switches, so the 12v wire is now ground and the ground is now a 12v, thus making it go up. but sometimes when mine goes down and you go to put it back up, it makes both wires 12v. think i got a wire touching the ground and making it hot? anyone had this problem? how would you trace this ?