My passenger window motor went out and i replaced it about 6 months ago. Replacing it with Dorman off amazon. Flashforward and now my window motor no longer works again but only after 6 months... Something is wrong here. So its stuck in the down position and im fiddling with everything trying to get it up so that i dont have to open the door panel. My car has the option to roll up or down window by holding the lock button or unlock button on the remote, well it goes up and down perfectly using that. Whats the problem and what do i need to fix. Im very DIY capable of anything on a car as i have a shop, so anything would help. Thanks!
TLDR: Passenger window only works when using the key remote by holding the unlock or lock button.

 

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So neither the switch in the driver's door nor the switch in the passenger's door will operate the passenger window? But the automatic roll-down/up does? At least you know the motor isn't the problem!

In case you don't have the manual, it's "gw.pdf" here:
http://www.nicoclub.com/FSM/G35/Coupe/2003/

That should help you trace it down. I believe the manual window control for both sides passes through the driver's door control panel. There may even be a small processor of some sort under those switches and I have read here of folks needing to replace that switch panel. That's just an idea, I hope you can locate the actual problem.