I have a 96 trans am convertible with passenger window issues. The window will not go down. I pulled the door panel and the motor out. Motor does work in one direction which I believe is up; because the window will not go down. I tried several switches and another known good motor and still the same outcome. Bought a new motor in case my "known good motor" was bad and still same result. Had issues with car not starting at one time, repaired the bcm and have had no problem since. Car is, and has not been on the road for over a year. ( paint, body work, tranny, top, interior ). Thank you for your expertise.

 

The switches and motors work by reversing polarity to the motor to make it go up then down. The fact that the motor will only go in one direction for your current motor and then also for the new motor would indicate that you have a wiring/switch problem.

The power for the motors are wired through the switch on the drivers side, then through the switch on the passenger side, and then to the motor in the passenger door.

My '99 has had several switches go out over the years. If you unplug the harness and look at the back side of them, you may even see one of the contacts melted, which is a tell-tale of a shot switch.

If you have a multi-tester, you can register at Autozone.com and get access to the wiring schematics for the window switches. You can then probe and test the switches to see which one is bad.