another question about the tailgate window!!

[Xearo69]

well not really! but ok i put a new tailgate window motor in beacause the last oone had the busshing obliterated. there was nothing but crap inside the motor. new one is great and it works too but only sometimes.. if i use a 12 from battery, it always works. when i go thru the harness, the key switch on the tail gate works but sometimes it doesnt. it seems like maybe the wires are lose going into it or maybe there is a break somewhere nearby and when i mess with the switch it makes things work.. u think its a break where the wires leave the tailgate out the left? or is the switch bad? ive allready bypassed the limit switch. oh and also, the driver switch only goes up... i checked voltage at the motor with the motor disconnected and the driver switch and key switch both do 12.5 and -12.5. however, with the motor connected it only sometimes works. when it doesnt, the volymeter shows 0 volts. this is a voltage collapse under load. i bet its a break or the wirre is so corroded it needs to be replaced. however, going off that wiring diagram, the wire colors change when it is at th driver area about to go into the fuse box. hmmm.. it must cvhange somewhere beyond the tail gate but before it gets tto the driver side front door... any suggestions?where do the wires change at? an what is causeing my voltage collapse?!!