vaman,
I don't have the diagrams in front of me now, but I can tell you how they work. For the sake of explaining we will talk about one of the front windows. The rear work the same but there 2 switches involved.
In this explanation we will assume a working system. With the ignition on, there will be power to the switch. The switch will pass the power to both wires going to the motor. When you depress the switch to up or down one of the wires is switched to ground while the other remains at 12V. Press the switch the other way and the same thing happens except this time the wire which was at ground is now 12V and the other wire is switched to ground. In other words the switch reverses the polarity to the motor. Just remember, when the switch is not depresses, both wires have 12V on them. If you don't have one, you should invest in a test light. To me, it is better than a volt meter once you get used to it. If you have a volt meter and can use it, it will also work. I hope this makes sense. If you have questions let us know.

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84 500 SEL (307,xxx miles)