A while back, the lock on the right rear passenger door of my car stopped locking. I was pretty bummed because I figured it was the lock motor had died or something and it seemed like a labor intensive and expensive fix. Then, today, I realized that the window on that door also wasn't opening. That made me suspect it was fuse related. Lo and behold, I pulled out the fuse for that door and it was dead. I replaced it and now the door locks and the window functions normally. A $10 fix.