Join Date: Jun 2006
Location: Eastern ON Canada
Car: 07 OBW 2.5i D-4AT
Feedback Score: 6 reviews
Referring to the second photo, the exposed copper lines appear to be the back of the switch. The actual contacts that the switch opens and closes to control the power to the window motor, are on the other side, under the rocker knob.
Bad contacts in the passenger side switch could not only prevent that switch from controlling the window, but as you report, it also affects the driver's side control for that window.
There are threads here with reports on repairing the switches in the main driver's control, and I would imagine the single passenger side would be similar. Basically, I believe the rocker part is removed, and this exposes the moving contacts and possibly some other small, easily lost, bits. The copper surfaces are often dirty, corroded, or worn, and correcting this returns the switch to full operation.
An alternative might be to buy a replacement switch from a dealer (local or on-line) or find a used one (from a recycler).
By the way, it's not a good idea to test for voltage by putting "something metal on the copper". That can cause additional problems that would make troubleshooting and correcting the situation even more difficult. Use a Voltmeter, or a test bulb.