What you call a "motion sensor" is actually a bunch of IR leds. That's it. It doesn't sense anything... the "sensors" are on the wiimote. The purpose of that IR led bar is to serve as a point of reference to the wiimote to know where it's pointing at. The picture isn't really clear enough to know what's going on, but did you check if you accidentally bridged anything? is the 12v pin to the sensor bar connector actually supplying 12v? what's that sketchy red wire going to the 12v pin of the connector? regardless, you don't actually need to plug the bar into the console itself, as the console is just supplying power to it. If you can manage to power the leds by other means or even use a 3rd party bar that's powered by something else, you can work around the issue.