Troubleshooting the electric circuitry is often feared but is very straightforward in reality.
Start with a copy or printout with the circuit diagram in question. We take an example here, the driver's side electric window of a Series 1 XM. A printout or a copy will enable you to take extensive notes on the diagram. Create as many as there are actual operating states of the circuit. In the case of the electric window, this might be: