I'd be willing to bet that the motion sensor is broken and/or wired wrong. We noticed not too long after we picked up our trailer that the pantry closet light never shut off. So one day I took a look at the wiring and it didn't make sense to me (I'm an Engineer), so I called Alliance and they sent me a diagram which proved that it wasn't wired right. So I took it all apart and rewired it correctly (based on the diagram that Alliance sent me). That's when I discovered that the sensor was broken and would never turn the light on. I have to assume that the tech in factory who did the original install also realized that the sensor was broken and rather than replace it, he ran another 12V power lead over to the sensor which basically bypassed it so the light always stayed on. Alliance sent me a new sensor and I wired it up and it now works fine.
I tried and failed to find the wiring diagram (actually a picture) that they sent me. If you call Alliance customer service I'll bet they can send it to you as well.