I have replaced the entire window motor/actuator assembly. The window motor was working (albeit on its last leg) prior to removing everything, and I've tried to run it with both the old and new motor/actuator unit and neither work. However, I've confirmed that both motors will work on the driver side, so the motors themselves aren't dead.

 

Try moving the harness between the body, and the door, around while testing. Might be a bad connection in there somewhere, that can mange the load of the LED, but, not the motor.

 

I tested both the passenger and driver sides with the multimeter and both had a signal of 11.83V when opening and closing the switch.

I opened up the harness between the door and the body to no avail, but as luck would have it as I closed the door the switch happened to activate as it was pressed against the body frame accidentally, and the motor moved. I noticed the harness for the motor was pinched, and only ran when it was pinched (still provided a light on the test light and 11.83v in this position). I opened up the actual connector for the motor and the lead for the down signal wire was loose in its socket. I crimped it down and added some gorilla glue for good measure to keep it in there. Gonna test it once it cures and cross my fingers, otherwise it's a trip to the junkyard to rip another motor socket out.

Thanks all for your help!