weastburn

Greetings from the Rocky Mountains! The driver-side automatic shoulder belt went out on our 92 Legacy wagon. The cable broke that pulls the sholder clip back & forth along the track in the door frame. Passenger side works fine. Went to the junkyard and got a replacement motor/track assembly off an identical 92. It had a bad limit switch, but otherwise, seemed fine. Replaced the limit switch & it worked 2X then stuck mid-way. I compared voltages wih the passenger side and didn't see -12V going to the driver-side motor. Voltages goes to the passenger-side just fine, polarity reverses as the motor runs back & forth along the track. Checked at the control unit & didn't see voltage there either. Ohms checked the wires between the motor and the control unit, they were good. Found another control unit (same make/model/part#) at the junkyard ($15), installed it and nothing changed. Does anyone have any ideas or have a good description of how this system works? The Haynes/Chilton manual is useless and the schematics I downloaded don't provide me a description of what makes the control unit do its thing. At this point, I'm suspecting the motor/track I got from the junkyard is a dud, but any other ideas that keep me out of the Subaru shop (or a 3rd trip to the junkyard) are most welcome!