1990 Volvo 245DL 222k miles

Question about the power window regulator motor: The motor has a red and black wire going to it. Am I correct in the assumption that the motor gets its ground from being mounted to the steel regulator that is mounted to the car door, and the motor will spin one way if the red wire gets 12V and spin the other way if the black gets 12V? I have the schematic for the power windows but I am not very adept at interpreting it.

 

The switch reverses the power. So, both wires are used. Red and black need to be + and - or - and + at the same time, to go one direction or reverse. The ground does not come from the case.

 

Yeah, that makes sense. Thanks.